chore(release): 4.5.3

Diff: https://github.com/socketio/socket.io/compare/4.5.2...4.5.3

.github/ISSUE_TEMPLATE/bug_report.md

@@ -2,7 +2,7 @@
 name: Bug report
 about: Create a report to help us improve
 title: ''
-labels: 'bug'
+labels: 'to triage'
 assignees: ''
 
 ---

.github/workflows/ci.yml

@@ -6,21 +6,31 @@ on:
   schedule:
     - cron: '0 0 * * 0'
 
+permissions:
+  contents: read
+
 jobs:
   test-node:
     runs-on: ubuntu-latest
+    timeout-minutes: 10
 
     strategy:
       matrix:
         node-version: [12, 14, 16]
 
     steps:
-      - uses: actions/checkout@v2
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
       - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@v2
+        uses: actions/setup-node@v3
         with:
           node-version: ${{ matrix.node-version }}
-      - run: npm ci
-      - run: npm test
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Run tests
+        run: npm test
         env:
           CI: true

CHANGELOG.md

@@ -1,3 +1,110 @@
+# History
+
+- [4.5.3](#453-2022-10-15) (2022-10-15)
+- [4.5.2](#452-2022-09-02) (2022-09-02)
+- [4.5.1](#451-2022-05-17) (2022-05-17)
+- [4.5.0](#450-2022-04-23) (2022-04-23)
+- [4.4.1](#441-2022-01-06) (2022-01-06)
+- [4.4.0](#440-2021-11-18) (2021-11-18)
+- [4.3.2](#432-2021-11-08) (2021-11-08)
+- [4.3.1](#431-2021-10-16) (2021-10-16)
+- [4.3.0](#430-2021-10-14) (2021-10-14)
+- [4.2.0](#420-2021-08-30) (2021-08-30)
+- [4.1.3](#413-2021-07-10) (2021-07-10)
+- [4.1.2](#412-2021-05-17) (2021-05-17)
+- [4.1.1](#411-2021-05-11) (2021-05-11)
+- [4.1.0](#410-2021-05-11) (2021-05-11)
+- [4.0.2](#402-2021-05-06) (2021-05-06)
+- [4.0.1](#401-2021-03-31) (2021-03-31)
+- [4.0.0](#400-2021-03-10) (2021-03-10)
+- [3.1.2](#312-2021-02-26) (2021-02-26)
+- [3.1.1](#311-2021-02-03) (2021-02-03)
+- [3.1.0](#310-2021-01-15) (2021-01-15)
+- [3.0.5](#305-2021-01-05) (2021-01-05)
+- [3.0.4](#304-2020-12-07) (2020-12-07)
+- [3.0.3](#303-2020-11-19) (2020-11-19)
+- [3.0.2](#302-2020-11-17) (2020-11-17)
+- [3.0.1](#301-2020-11-09) (2020-11-09)
+- [3.0.0](#300-2020-11-05) (2020-11-05)
+
+# Release notes
+
+## [4.5.3](https://github.com/socketio/socket.io/compare/4.5.2...4.5.3) (2022-10-15)
+
+
+### Bug Fixes
+
+* **typings:** accept an HTTP2 server in the constructor ([d3d0a2d](https://github.com/socketio/socket.io/commit/d3d0a2d5beaff51fd145f810bcaf6914213f8a06))
+* **typings:** apply types to "io.timeout(...).emit()" calls ([e357daf](https://github.com/socketio/socket.io/commit/e357daf5858560bc84e7e50cd36f0278d6721ea1))
+
+
+
+## [4.5.2](https://github.com/socketio/socket.io/compare/4.5.1...4.5.2) (2022-09-02)
+
+
+### Bug Fixes
+
+* prevent the socket from joining a room after disconnection ([18f3fda](https://github.com/socketio/socket.io/commit/18f3fdab12947a9fee3e9c37cfc1da97027d1473))
+* **uws:** prevent the server from crashing after upgrade ([ba497ee](https://github.com/socketio/socket.io/commit/ba497ee3eb52c4abf1464380d015d8c788714364))
+
+
+
+## [4.5.1](https://github.com/socketio/socket.io/compare/4.5.0...4.5.1) (2022-05-17)
+
+
+### Bug Fixes
+
+* forward the local flag to the adapter when using fetchSockets() ([30430f0](https://github.com/socketio/socket.io/commit/30430f0985f8e7c49394543d4c84913b6a15df60))
+* **typings:** add HTTPS server to accepted types ([#4351](https://github.com/socketio/socket.io/issues/4351)) ([9b43c91](https://github.com/socketio/socket.io/commit/9b43c9167cff817c60fa29dbda2ef7cd938aff51))
+
+
+
+# [4.5.0](https://github.com/socketio/socket.io/compare/4.4.1...4.5.0) (2022-04-23)
+
+
+### Bug Fixes
+
+* **typings:** ensure compatibility with TypeScript 3.x ([#4259](https://github.com/socketio/socket.io/issues/4259)) ([02c87a8](https://github.com/socketio/socket.io/commit/02c87a85614e217b8e7b93753f315790ae9d99f6))
+
+
+### Features
+
+* add support for catch-all listeners for outgoing packets ([531104d](https://github.com/socketio/socket.io/commit/531104d332690138b7aab84d5583d6204132c8b4))
+
+This is similar to `onAny()`, but for outgoing packets.
+
+Syntax:
+
+```js
+socket.onAnyOutgoing((event, ...args) => {
+  console.log(event);
+});
+```
+
+* broadcast and expect multiple acks ([8b20457](https://github.com/socketio/socket.io/commit/8b204570a94979bbec307f23ca078f30f5cf07b0))
+
+Syntax:
+
+```js
+io.timeout(1000).emit("some-event", (err, responses) => {
+  // ...
+});
+```
+
+* add the "maxPayload" field in the handshake details ([088dcb4](https://github.com/socketio/engine.io/commit/088dcb4dff60df39785df13d0a33d3ceaa1dff38))
+
+So that clients in HTTP long-polling can decide how many packets they have to send to stay under the maxHttpBufferSize
+value.
+
+This is a backward compatible change which should not mandate a new major revision of the protocol (we stay in v4), as
+we only add a field in the JSON-encoded handshake data:
+
+```
+0{"sid":"lv_VI97HAXpY6yYWAAAC","upgrades":["websocket"],"pingInterval":25000,"pingTimeout":5000,"maxPayload":1000000}
+```
+
+
+
 ## [4.4.1](https://github.com/socketio/socket.io/compare/4.4.0...4.4.1) (2022-01-06)
 
 

Readme.md

@@ -2,8 +2,6 @@
 [![Run on Repl.it](https://repl.it/badge/github/socketio/socket.io)](https://replit.com/@socketio/socketio-minimal-example)
 [![Backers on Open Collective](https://opencollective.com/socketio/backers/badge.svg)](#backers) [![Sponsors on Open Collective](https://opencollective.com/socketio/sponsors/badge.svg)](#sponsors)
 [![Build Status](https://github.com/socketio/socket.io/workflows/CI/badge.svg)](https://github.com/socketio/socket.io/actions)
-[![Dependency Status](https://david-dm.org/socketio/socket.io.svg)](https://david-dm.org/socketio/socket.io)
-[![devDependency Status](https://david-dm.org/socketio/socket.io/dev-status.svg)](https://david-dm.org/socketio/socket.io#info=devDependencies)
 [![NPM version](https://badge.fury.io/js/socket.io.svg)](https://www.npmjs.com/package/socket.io)
 ![Downloads](https://img.shields.io/npm/dm/socket.io.svg?style=flat)
 [![](https://slackin-socketio.now.sh/badge.svg)](https://slackin-socketio.now.sh)

examples/basic-crud-application/README.md

@@ -2,6 +2,13 @@
 
 Please read the related [guide](https://socket.io/get-started/basic-crud-application/).
 
+This repository contains several implementations of the server:
+
+| Directory                  | Language   | Database                                                                           | Cluster?                                                                                   |
+|----------------------------|------------|------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------|
+| `server/`                  | TypeScript | in-memory                                                                          | No                                                                                         |
+| `server-postgres-cluster/` | JavaScript | Postgres, with the [Postgres adapter](https://socket.io/docs/v4/postgres-adapter/) | Yes, with the [`@socket.io/sticky`](https://github.com/socketio/socket.io-sticky) module)  |
+
 ## Running the frontend
 
 ```

examples/basic-crud-application/angular-client/package.json

@@ -37,7 +37,7 @@
     "karma-chrome-launcher": "~3.1.0",
     "karma-coverage": "~2.0.3",
     "karma-jasmine": "~4.0.0",
-    "karma-jasmine-html-reporter": "^1.5.0",
+    "karma-jasmine-html-reporter": "~1.5.0",
     "protractor": "~7.0.0",
     "ts-node": "~8.3.0",
     "tslint": "~6.1.0",

examples/basic-crud-application/server-postgres-cluster/README.md

@@ -0,0 +1,16 @@
+
+A basic TODO project.
+
+| Characteristic |                                                                                           |
+|----------------|-------------------------------------------------------------------------------------------|
+| Language       | plain JavaScript                                                                          |
+| Database       | Postgres, with the [Postgres adapter](https://socket.io/docs/v4/postgres-adapter/)        |
+| Cluster?       | Yes, with the [`@socket.io/sticky`](https://github.com/socketio/socket.io-sticky) module) |
+
+## Usage
+
+```
+$ docker-compose up -d
+$ npm install
+$ npm start
+```

examples/basic-crud-application/server-postgres-cluster/docker-compose.yml

@@ -0,0 +1,9 @@
+version: "3"
+
+services:
+  postgres:
+    image: postgres:12
+    ports:
+      - "5432:5432"
+    environment:
+      POSTGRES_PASSWORD: "changeit"

examples/basic-crud-application/server-postgres-cluster/lib/app.js

@@ -0,0 +1,26 @@
+import { Server } from "socket.io";
+import createTodoHandlers from "./todo-management/todo.handlers.js";
+import { setupWorker } from "@socket.io/sticky";
+import { createAdapter } from "@socket.io/postgres-adapter";
+
+export function createApplication(httpServer, components, serverOptions = {}) {
+  const io = new Server(httpServer, serverOptions);
+
+  const { createTodo, readTodo, updateTodo, deleteTodo, listTodo } =
+    createTodoHandlers(components);
+
+  io.on("connection", (socket) => {
+    socket.on("todo:create", createTodo);
+    socket.on("todo:read", readTodo);
+    socket.on("todo:update", updateTodo);
+    socket.on("todo:delete", deleteTodo);
+    socket.on("todo:list", listTodo);
+  });
+
+  // enable sticky session in the cluster (to remove in standalone mode)
+  setupWorker(io);
+
+  io.adapter(createAdapter(components.connectionPool));
+
+  return io;
+}

examples/basic-crud-application/server-postgres-cluster/lib/cluster.js

@@ -0,0 +1,28 @@
+import cluster from "cluster";
+import { createServer } from "http";
+import { setupMaster } from "@socket.io/sticky";
+import { cpus } from "os";
+
+if (cluster.isMaster) {
+  console.log(`Master ${process.pid} is running`);
+  const httpServer = createServer();
+
+  setupMaster(httpServer, {
+    loadBalancingMethod: "least-connection",
+  });
+
+  httpServer.listen(3000);
+
+  for (let i = 0; i < cpus().length; i++) {
+    cluster.fork();
+  }
+
+  cluster.on("exit", (worker) => {
+    console.log(`Worker ${worker.process.pid} died`);
+    cluster.fork();
+  });
+} else {
+  console.log(`Worker ${process.pid} started`);
+
+  import("./index.js");
+}

examples/basic-crud-application/server-postgres-cluster/lib/index.js

@@ -0,0 +1,51 @@
+import { createServer } from "http";
+import { createApplication } from "./app.js";
+import { Sequelize } from "sequelize";
+import pg from "pg";
+import { PostgresTodoRepository } from "./todo-management/todo.repository.js";
+
+const httpServer = createServer();
+
+const sequelize = new Sequelize("postgres", "postgres", "changeit", {
+  dialect: "postgres",
+});
+
+const connectionPool = new pg.Pool({
+  user: "postgres",
+  host: "localhost",
+  database: "postgres",
+  password: "changeit",
+  port: 5432,
+});
+
+createApplication(
+  httpServer,
+  {
+    connectionPool,
+    todoRepository: new PostgresTodoRepository(sequelize),
+  },
+  {
+    cors: {
+      origin: ["http://localhost:4200"],
+    },
+  }
+);
+
+const main = async () => {
+  // create the tables if they do not exist already
+  await sequelize.sync();
+
+  // create the table needed by the postgres adapter
+  await connectionPool.query(`
+    CREATE TABLE IF NOT EXISTS socket_io_attachments (
+        id          bigserial UNIQUE,
+        created_at  timestamptz DEFAULT NOW(),
+        payload     bytea
+    );
+  `);
+
+  // uncomment when running in standalone mode
+  // httpServer.listen(3000);
+};
+
+main();

examples/basic-crud-application/server-postgres-cluster/lib/todo-management/todo.handlers.js

@@ -0,0 +1,140 @@
+import { Errors, mapErrorDetails, sanitizeErrorMessage } from "../util.js";
+import { v4 as uuid } from "uuid";
+import Joi from "joi";
+
+const idSchema = Joi.string().guid({
+  version: "uuidv4",
+});
+
+const todoSchema = Joi.object({
+  id: idSchema.alter({
+    create: (schema) => schema.forbidden(),
+    update: (schema) => schema.required(),
+  }),
+  title: Joi.string().max(256).required(),
+  completed: Joi.boolean().required(),
+});
+
+export default function (components) {
+  const { todoRepository } = components;
+  return {
+    createTodo: async function (payload, callback) {
+      const socket = this;
+
+      // validate the payload
+      const { error, value } = todoSchema.tailor("create").validate(payload, {
+        abortEarly: false,
+        stripUnknown: true,
+      });
+
+      if (error) {
+        return callback({
+          error: Errors.INVALID_PAYLOAD,
+          errorDetails: mapErrorDetails(error.details),
+        });
+      }
+
+      value.id = uuid();
+
+      // persist the entity
+      try {
+        await todoRepository.save(value);
+      } catch (e) {
+        return callback({
+          error: sanitizeErrorMessage(e),
+        });
+      }
+
+      // acknowledge the creation
+      callback({
+        data: value.id,
+      });
+
+      // notify the other users
+      socket.broadcast.emit("todo:created", value);
+    },
+
+    readTodo: async function (id, callback) {
+      const { error } = idSchema.validate(id);
+
+      if (error) {
+        return callback({
+          error: Errors.ENTITY_NOT_FOUND,
+        });
+      }
+
+      try {
+        const todo = await todoRepository.findById(id);
+        callback({
+          data: todo,
+        });
+      } catch (e) {
+        callback({
+          error: sanitizeErrorMessage(e),
+        });
+      }
+    },
+
+    updateTodo: async function (payload, callback) {
+      const socket = this;
+
+      const { error, value } = todoSchema.tailor("update").validate(payload, {
+        abortEarly: false,
+        stripUnknown: true,
+      });
+
+      if (error) {
+        return callback({
+          error: Errors.INVALID_PAYLOAD,
+          errorDetails: mapErrorDetails(error.details),
+        });
+      }
+
+      try {
+        await todoRepository.save(value);
+      } catch (e) {
+        return callback({
+          error: sanitizeErrorMessage(e),
+        });
+      }
+
+      callback();
+      socket.broadcast.emit("todo:updated", value);
+    },
+
+    deleteTodo: async function (id, callback) {
+      const socket = this;
+
+      const { error } = idSchema.validate(id);
+
+      if (error) {
+        return callback({
+          error: Errors.ENTITY_NOT_FOUND,
+        });
+      }
+
+      try {
+        await todoRepository.deleteById(id);
+      } catch (e) {
+        return callback({
+          error: sanitizeErrorMessage(e),
+        });
+      }
+
+      callback();
+      socket.broadcast.emit("todo:deleted", id);
+    },
+
+    listTodo: async function (callback) {
+      try {
+        callback({
+          data: await todoRepository.findAll(),
+        });
+      } catch (e) {
+        callback({
+          error: sanitizeErrorMessage(e),
+        });
+      }
+    },
+  };
+}

examples/basic-crud-application/server-postgres-cluster/lib/todo-management/todo.repository.js

@@ -0,0 +1,74 @@
+import { Errors } from "../util.js";
+import { Model, DataTypes } from "sequelize";
+
+class CrudRepository {
+  findAll() {}
+  findById(id) {}
+  save(entity) {}
+  deleteById(id) {}
+}
+
+export class TodoRepository extends CrudRepository {}
+
+class Todo extends Model {}
+
+export class PostgresTodoRepository extends TodoRepository {
+  constructor(sequelize) {
+    super();
+    this.sequelize = sequelize;
+
+    Todo.init(
+      {
+        id: {
+          type: DataTypes.STRING,
+          primaryKey: true,
+          allowNull: false,
+        },
+        title: {
+          type: DataTypes.STRING,
+        },
+        completed: {
+          type: DataTypes.BOOLEAN,
+        },
+      },
+      {
+        sequelize,
+        tableName: "todos",
+      }
+    );
+  }
+
+  findAll() {
+    return this.sequelize.transaction((transaction) => {
+      return Todo.findAll({ transaction });
+    });
+  }
+
+  async findById(id) {
+    return this.sequelize.transaction(async (transaction) => {
+      const todo = await Todo.findByPk(id, { transaction });
+
+      if (!todo) {
+        throw Errors.ENTITY_NOT_FOUND;
+      }
+
+      return todo;
+    });
+  }
+
+  save(entity) {
+    return this.sequelize.transaction((transaction) => {
+      return Todo.upsert(entity, { transaction });
+    });
+  }
+
+  async deleteById(id) {
+    return this.sequelize.transaction(async (transaction) => {
+      const count = await Todo.destroy({ where: { id }, transaction });
+
+      if (count === 0) {
+        throw Errors.ENTITY_NOT_FOUND;
+      }
+    });
+  }
+}

examples/basic-crud-application/server-postgres-cluster/lib/util.js

@@ -0,0 +1,22 @@
+export const Errors = {
+  ENTITY_NOT_FOUND: "entity not found",
+  INVALID_PAYLOAD: "invalid payload",
+};
+
+const errorValues = Object.values(Errors);
+
+export function sanitizeErrorMessage(message) {
+  if (typeof message === "string" && errorValues.includes(message)) {
+    return message;
+  } else {
+    return "an unknown error has occurred";
+  }
+}
+
+export function mapErrorDetails(details) {
+  return details.map((item) => ({
+    message: item.message,
+    path: item.path,
+    type: item.type,
+  }));
+}

examples/basic-crud-application/server-postgres-cluster/package.json

@@ -0,0 +1,30 @@
+{
+  "name": "basic-crud-server",
+  "version": "0.0.1",
+  "description": "Server for the Basic CRUD Socket.IO example (with Postgres and multiple Socket.IO servers)",
+  "main": "lib/cluster.js",
+  "type": "module",
+  "scripts": {
+    "start": "node lib/cluster.js"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/socketio/socket.io.git"
+  },
+  "author": "Damien Arrachequesne <damien.arrachequesne@gmail.com>",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/socketio/socket.io/issues"
+  },
+  "homepage": "https://github.com/socketio/socket.io#readme",
+  "dependencies": {
+    "@socket.io/postgres-adapter": "^0.2.0",
+    "@socket.io/sticky": "^1.0.1",
+    "joi": "^17.4.0",
+    "pg": "^8.7.3",
+    "pg-hstore": "^2.3.4",
+    "sequelize": "^6.18.0",
+    "socket.io": "^4.0.1",
+    "uuid": "^8.3.2"
+  }
+}

examples/basic-crud-application/server/package.json

@@ -24,14 +24,14 @@
     "uuid": "^8.3.2"
   },
   "devDependencies": {
-    "@types/mocha": "^8.2.3",
     "@types/chai": "^4.2.16",
+    "@types/mocha": "^10.0.0",
     "@types/uuid": "^8.3.0",
     "chai": "^4.3.4",
-    "mocha": "^8.3.2",
+    "mocha": "^10.0.0",
     "nyc": "^15.1.0",
     "socket.io-client": "^4.0.1",
-    "ts-node": "^9.1.1",
+    "ts-node": "^10.9.1",
     "typescript": "^4.2.4"
   }
 }

examples/create-react-app-example/src/App.js

@@ -1,4 +1,5 @@
 import React, { useState, useEffect } from 'react';
+import logo from './logo.svg';
 import './App.css';
 import io from 'socket.io-client';
 
@@ -23,7 +24,7 @@ function App() {
       socket.off('disconnect');
       socket.off('message');
     };
-  });
+  }, []);
 
   const sendMessage = () => {
     socket.emit('hello!');
@@ -32,9 +33,21 @@ function App() {
   return (
     <div className="App">
       <header className="App-header">
+        <img src={logo} className="App-logo" alt="logo" />
         <p>Connected: { '' + isConnected }</p>
         <p>Last message: { lastMessage || '-' }</p>
         <button onClick={ sendMessage }>Say hello!</button>
+        <p>
+          Edit <code>src/App.js</code> and save to reload.
+        </p>
+        <a
+          className="App-link"
+          href="https://reactjs.org"
+          target="_blank"
+          rel="noopener noreferrer"
+        >
+          Learn React
+        </a>
       </header>
     </div>
   );

examples/express-session-example/README.md

@@ -0,0 +1,16 @@
+# Example with [express-session](https://www.npmjs.com/package/express-session)
+
+This example shows how to share a session context between [Express](http://expressjs.com/) and [Socket.IO](https://socket.io/docs/v4/):
+
+![Video of the example](assets/demo.gif)
+
+Please read the related guide: https://socket.io/how-to/use-with-express-session
+
+## How to use
+
+```
+$ npm install
+$ npm start
+```
+
+And point your browser to `http://localhost:3000`. Optionally, specify a port by supplying the `PORT` env variable.

examples/express-session-example/index.html

@@ -0,0 +1,57 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <title>Example with express-session</title>
+  </head>
+  <body>
+    <button onclick="incrementWithFetch()">Increment with fetch()</button>
+    <button onclick="logout()">Logout</button>
+    <p>Count: <span id="httpCount">0</span></p>
+
+    <button onclick="incrementWithEmit()">
+      Increment with Socket.IO emit()
+    </button>
+    <p>Status: <span id="ioStatus">disconnected</span></p>
+    <p>Count: <span id="ioCount">0</span></p>
+
+    <script src="/socket.io/socket.io.js"></script>
+    <script>
+      const httpCount = document.getElementById("httpCount");
+      const ioStatus = document.getElementById("ioStatus");
+      const ioCount = document.getElementById("ioCount");
+
+      const socket = io({
+        // with WebSocket only
+        // transports: ["websocket"],
+      });
+
+      async function incrementWithFetch() {
+        const response = await fetch("/incr", {
+          method: "post",
+        });
+        httpCount.innerText = await response.text();
+      }
+
+      function logout() {
+        fetch("/logout", {
+          method: "post",
+        });
+      }
+
+      async function incrementWithEmit() {
+        socket.emit("incr", (count) => {
+          ioCount.innerText = count;
+        });
+      }
+
+      socket.on("connect", () => {
+        ioStatus.innerText = "connected";
+      });
+
+      socket.on("disconnect", () => {
+        ioStatus.innerText = "disconnected";
+      });
+    </script>
+  </body>
+</html>

examples/express-session-example/index.js

@@ -0,0 +1,91 @@
+import express from "express";
+import { createServer } from "http";
+import { Server } from "socket.io";
+import session from "express-session";
+
+const port = process.env.PORT || 3000;
+
+const app = express();
+const httpServer = createServer(app);
+
+const sessionMiddleware = session({
+  secret: "changeit",
+  resave: true,
+  saveUninitialized: true,
+});
+
+app.use(sessionMiddleware);
+
+app.get("/", (req, res) => {
+  res.sendFile("./index.html", { root: process.cwd() });
+});
+
+app.post("/incr", (req, res) => {
+  const session = req.session;
+  session.count = (session.count || 0) + 1;
+  res.status(200).end("" + session.count);
+});
+
+app.post("/logout", (req, res) => {
+  const sessionId = req.session.id;
+  req.session.destroy(() => {
+    // disconnect all Socket.IO connections linked to this session ID
+    io.to(sessionId).disconnectSockets();
+    res.status(204).end();
+  });
+});
+
+const io = new Server(httpServer, {
+  allowRequest: (req, callback) => {
+    // with HTTP long-polling, we have access to the HTTP response here, but this is not
+    // the case with WebSocket, so we provide a dummy response object
+    const fakeRes = {
+      getHeader() {
+        return [];
+      },
+      setHeader(key, values) {
+        req.cookieHolder = values[0];
+      },
+      writeHead() {},
+    };
+    sessionMiddleware(req, fakeRes, () => {
+      if (req.session) {
+        // trigger the setHeader() above
+        fakeRes.writeHead();
+        // manually save the session (normally triggered by res.end())
+        req.session.save();
+      }
+      callback(null, true);
+    });
+  },
+});
+
+io.engine.on("initial_headers", (headers, req) => {
+  if (req.cookieHolder) {
+    headers["set-cookie"] = req.cookieHolder;
+    delete req.cookieHolder;
+  }
+});
+
+io.on("connect", (socket) => {
+  const req = socket.request;
+
+  socket.join(req.session.id);
+
+  socket.on("incr", (cb) => {
+    req.session.reload((err) => {
+      if (err) {
+        // session has expired
+        return socket.disconnect();
+      }
+      req.session.count = (req.session.count || 0) + 1;
+      req.session.save(() => {
+        cb(req.session.count);
+      });
+    });
+  });
+});
+
+httpServer.listen(port, () => {
+  console.log(`application is running at: http://localhost:${port}`);
+});

examples/express-session-example/package.json

@@ -0,0 +1,15 @@
+{
+  "name": "express-session-example",
+  "version": "0.0.1",
+  "private": true,
+  "type": "module",
+  "description": "Example with express-session (https://github.com/expressjs/session)",
+  "scripts": {
+    "start": "node index.js"
+  },
+  "dependencies": {
+    "express": "~4.17.3",
+    "express-session": "~1.17.2",
+    "socket.io": "~4.4.1"
+  }
+}

examples/rollup-server-bundle/.gitignore

@@ -0,0 +1 @@
+bundle.js

examples/rollup-server-bundle/index.js

@@ -0,0 +1,3 @@
+import { Server } from "socket.io";
+
+new Server(0);

examples/rollup-server-bundle/package.json

@@ -0,0 +1,19 @@
+{
+  "name": "rollup-server-bundle",
+  "version": "0.0.1",
+  "description": "",
+  "main": "index.js",
+  "type": "module",
+  "author": "Damien Arrachequesne <damien.arrachequesne@gmail.com>",
+  "license": "ISC",
+  "scripts": {
+    "build": "rollup --config rollup.config.js"
+  },
+  "devDependencies": {
+    "@rollup/plugin-commonjs": "^21.0.3",
+    "@rollup/plugin-json": "^4.1.0",
+    "@rollup/plugin-node-resolve": "^13.1.3",
+    "rollup": "^2.70.1",
+    "socket.io": "^4.4.1"
+  }
+}

examples/rollup-server-bundle/rollup.config.js

@@ -0,0 +1,12 @@
+import resolve from "@rollup/plugin-node-resolve";
+import commonjs from "@rollup/plugin-commonjs";
+import json from "@rollup/plugin-json";
+
+export default {
+  input: "index.js",
+  output: {
+    file: "bundle.js",
+    format: "esm",
+  },
+  plugins: [resolve(), commonjs(), json({ compact: true })],
+};

examples/webpack-build/README.md

@@ -7,14 +7,5 @@ A sample Webpack build for the browser.
 
 ```
 $ npm i
-$ npm run build-all
+$ npm run build
 ```
-
-There are two WebPack configuration:
-
-- the minimal configuration, just bundling the application and its dependencies. The `app.js` file in the `dist` folder is the result of that build.
-
-- a slimmer one, where:
-  - the JSON polyfill needed for IE6/IE7 support has been removed.
-  - the `debug` calls and import have been removed (the [debug](https://github.com/visionmedia/debug) library is included in the build by default).
-  - the source has been uglified (dropping IE8 support), and an associated SourceMap has been generated.

examples/webpack-build/index.html

@@ -6,8 +6,7 @@
 </head>
 <body>
 
-  <!-- <script src="dist/app.js"></script> -->
-  <script src="dist/app.slim.js"></script>
+  <script src="dist/bundle.js"></script>
 
 </body>
-</html>
+</html>

examples/webpack-build/index.js

@@ -0,0 +1,15 @@
+import { io } from "socket.io-client";
+
+const socket = io("http://localhost:3000");
+
+socket.on("connect", () => {
+  console.log(`connect ${socket.id}`);
+});
+
+socket.on("connect_error", (err) => {
+  console.log(`connect_error due to ${err.message}`);
+});
+
+socket.on("disconnect", (reason) => {
+  console.log(`disconnect due to ${reason}`);
+});

examples/webpack-build/lib/index.js

@@ -1,12 +0,0 @@
-
-import io from 'socket.io-client';
-
-const socket = io('http://localhost:3000');
-
-console.log('init');
-
-socket.on('connect', onConnect);
-
-function onConnect(){
-  console.log('connect ' + socket.id);
-}

examples/webpack-build/package.json

@@ -2,20 +2,15 @@
   "name": "webpack-build",
   "version": "1.0.0",
   "description": "A sample Webpack build",
+  "type": "module",
   "scripts": {
-    "build": "webpack --config ./support/webpack.config.js",
-    "build-slim": "webpack --config ./support/webpack.config.slim.js",
-    "build-json-parser": "webpack --config ./support/webpack.config.json-parser.js",
-    "build-all": "npm run build && npm run build-slim && npm run build-json-parser"
+    "build": "webpack"
   },
   "author": "Damien Arrachequesne",
   "license": "MIT",
   "dependencies": {
-    "socket.io-client": "^2.0.2",
-    "socket.io-json-parser": "^2.1.0"
-  },
-  "devDependencies": {
-    "strip-loader": "^0.1.2",
-    "webpack": "^2.6.1"
+    "socket.io-client": "^4.4.1",
+    "webpack": "^5.72.0",
+    "webpack-cli": "^4.9.2"
   }
 }

examples/webpack-build/support/noop.js

@@ -1,2 +0,0 @@
-
-module.exports = function () { return function () {}; };

examples/webpack-build/support/webpack.config.js

@@ -1,8 +0,0 @@
-
-module.exports = {
-  entry: './lib/index.js',
-  output: {
-    path: require('path').join(__dirname, '../dist'),
-    filename: 'app.js'
-  }
-};

examples/webpack-build/support/webpack.config.json-parser.js

@@ -1,33 +0,0 @@
-
-var webpack = require('webpack');
-
-module.exports = {
-  entry: './lib/index.js',
-  output: {
-    path: require('path').join(__dirname, '../dist'),
-    filename: 'app.json-parser.js'
-  },
-  // generate sourcemap
-  devtool: 'source-map',
-  plugins: [
-    // replace require('debug')() with an noop function
-    new webpack.NormalModuleReplacementPlugin(/debug/, process.cwd() + '/support/noop.js'),
-    // replace socket.io-parser with socket.io-json-parser
-    new webpack.NormalModuleReplacementPlugin(/socket\.io-parser/, 'socket.io-json-parser'),
-    // use uglifyJS (IE9+ support)
-    new webpack.optimize.UglifyJsPlugin({
-      compress: {
-        warnings: false
-      }
-    })
-  ],
-  module: {
-    loaders: [
-      {
-        // strip `debug()` calls
-        test: /\.js$/,
-        loader: 'strip-loader?strip[]=debug'
-      }
-    ]
-  }
-};

examples/webpack-build/support/webpack.config.slim.js

@@ -1,31 +0,0 @@
-
-var webpack = require('webpack');
-
-module.exports = {
-  entry: './lib/index.js',
-  output: {
-    path: require('path').join(__dirname, '../dist'),
-    filename: 'app.slim.js'
-  },
-  // generate sourcemap
-  devtool: 'source-map',
-  plugins: [
-    // replace require('debug')() with an noop function
-    new webpack.NormalModuleReplacementPlugin(/debug/, process.cwd() + '/support/noop.js'),
-    // use uglifyJS (IE9+ support)
-    new webpack.optimize.UglifyJsPlugin({
-      compress: {
-        warnings: false
-      }
-    })
-  ],
-  module: {
-    loaders: [
-      {
-        // strip `debug()` calls
-        test: /\.js$/,
-        loader: 'strip-loader?strip[]=debug'
-      }
-    ]
-  }
-};

examples/webpack-build/webpack.config.js

@@ -0,0 +1,7 @@
+export default {
+  entry: "./index.js",
+  mode: "production",
+  output: {
+    filename: "bundle.js",
+  },
+};

lib/broadcast-operator.ts

@@ -22,18 +22,27 @@ export class BroadcastOperator<EmitEvents extends EventsMap, SocketData>
   /**
    * Targets a room when emitting.
    *
-   * @param room
-   * @return a new BroadcastOperator instance
-   * @public
+   * @example
+   * // the “foo” event will be broadcast to all connected clients in the “room-101” room
+   * io.to("room-101").emit("foo", "bar");
+   *
+   * // with an array of rooms (a client will be notified at most once)
+   * io.to(["room-101", "room-102"]).emit("foo", "bar");
+   *
+   * // with multiple chained calls
+   * io.to("room-101").to("room-102").emit("foo", "bar");
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public to(room: Room | Room[]): BroadcastOperator<EmitEvents, SocketData> {
+  public to(room: Room | Room[]) {
     const rooms = new Set(this.rooms);
     if (Array.isArray(room)) {
       room.forEach((r) => rooms.add(r));
     } else {
       rooms.add(room);
     }
-    return new BroadcastOperator(
+    return new BroadcastOperator<EmitEvents, SocketData>(
       this.adapter,
       rooms,
       this.exceptRooms,
@@ -42,33 +51,43 @@ export class BroadcastOperator<EmitEvents extends EventsMap, SocketData>
   }
 
   /**
-   * Targets a room when emitting.
+   * Targets a room when emitting. Similar to `to()`, but might feel clearer in some cases:
    *
-   * @param room
-   * @return a new BroadcastOperator instance
-   * @public
+   * @example
+   * // disconnect all clients in the "room-101" room
+   * io.in("room-101").disconnectSockets();
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public in(room: Room | Room[]): BroadcastOperator<EmitEvents, SocketData> {
+  public in(room: Room | Room[]) {
     return this.to(room);
   }
 
   /**
    * Excludes a room when emitting.
    *
-   * @param room
-   * @return a new BroadcastOperator instance
-   * @public
+   * @example
+   * // the "foo" event will be broadcast to all connected clients, except the ones that are in the "room-101" room
+   * io.except("room-101").emit("foo", "bar");
+   *
+   * // with an array of rooms
+   * io.except(["room-101", "room-102"]).emit("foo", "bar");
+   *
+   * // with multiple chained calls
+   * io.except("room-101").except("room-102").emit("foo", "bar");
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public except(
-    room: Room | Room[]
-  ): BroadcastOperator<EmitEvents, SocketData> {
+  public except(room: Room | Room[]) {
     const exceptRooms = new Set(this.exceptRooms);
     if (Array.isArray(room)) {
       room.forEach((r) => exceptRooms.add(r));
     } else {
       exceptRooms.add(room);
     }
-    return new BroadcastOperator(
+    return new BroadcastOperator<EmitEvents, SocketData>(
       this.adapter,
       this.rooms,
       exceptRooms,
@@ -79,15 +98,15 @@ export class BroadcastOperator<EmitEvents extends EventsMap, SocketData>
   /**
    * Sets the compress flag.
    *
+   * @example
+   * io.compress(false).emit("hello");
+   *
    * @param compress - if `true`, compresses the sending data
    * @return a new BroadcastOperator instance
-   * @public
    */
-  public compress(
-    compress: boolean
-  ): BroadcastOperator<EmitEvents, SocketData> {
+  public compress(compress: boolean) {
     const flags = Object.assign({}, this.flags, { compress });
-    return new BroadcastOperator(
+    return new BroadcastOperator<EmitEvents, SocketData>(
       this.adapter,
       this.rooms,
       this.exceptRooms,
@@ -100,12 +119,14 @@ export class BroadcastOperator<EmitEvents extends EventsMap, SocketData>
    * receive messages (because of network slowness or other issues, or because they’re connected through long polling
    * and is in the middle of a request-response cycle).
    *
+   * @example
+   * io.volatile.emit("hello"); // the clients may or may not receive it
+   *
    * @return a new BroadcastOperator instance
-   * @public
    */
-  public get volatile(): BroadcastOperator<EmitEvents, SocketData> {
+  public get volatile() {
     const flags = Object.assign({}, this.flags, { volatile: true });
-    return new BroadcastOperator(
+    return new BroadcastOperator<EmitEvents, SocketData>(
       this.adapter,
       this.rooms,
       this.exceptRooms,
@@ -116,12 +137,39 @@ export class BroadcastOperator<EmitEvents extends EventsMap, SocketData>
   /**
    * Sets a modifier for a subsequent event emission that the event data will only be broadcast to the current node.
    *
-   * @return a new BroadcastOperator instance
-   * @public
+   * @example
+   * // the “foo” event will be broadcast to all connected clients on this node
+   * io.local.emit("foo", "bar");
+   *
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public get local(): BroadcastOperator<EmitEvents, SocketData> {
+  public get local() {
     const flags = Object.assign({}, this.flags, { local: true });
-    return new BroadcastOperator(
+    return new BroadcastOperator<EmitEvents, SocketData>(
+      this.adapter,
+      this.rooms,
+      this.exceptRooms,
+      flags
+    );
+  }
+
+  /**
+   * Adds a timeout in milliseconds for the next operation
+   *
+   * @example
+   * io.timeout(1000).emit("some-event", (err, responses) => {
+   *   if (err) {
+   *     // some clients did not acknowledge the event in the given delay
+   *   } else {
+   *     console.log(responses); // one response per client
+   *   }
+   * });
+   *
+   * @param timeout
+   */
+  public timeout(timeout: number) {
+    const flags = Object.assign({}, this.flags, { timeout });
+    return new BroadcastOperator<EmitEvents, SocketData>(
       this.adapter,
       this.rooms,
       this.exceptRooms,
@@ -132,15 +180,30 @@ export class BroadcastOperator<EmitEvents extends EventsMap, SocketData>
   /**
    * Emits to all clients.
    *
+   * @example
+   * // the “foo” event will be broadcast to all connected clients
+   * io.emit("foo", "bar");
+   *
+   * // the “foo” event will be broadcast to all connected clients in the “room-101” room
+   * io.to("room-101").emit("foo", "bar");
+   *
+   * // with an acknowledgement expected from all connected clients
+   * io.timeout(1000).emit("some-event", (err, responses) => {
+   *   if (err) {
+   *     // some clients did not acknowledge the event in the given delay
+   *   } else {
+   *     console.log(responses); // one response per client
+   *   }
+   * });
+   *
    * @return Always true
-   * @public
    */
   public emit<Ev extends EventNames<EmitEvents>>(
     ev: Ev,
     ...args: EventParams<EmitEvents, Ev>
   ): boolean {
     if (RESERVED_EVENTS.has(ev)) {
-      throw new Error(`"${ev}" is a reserved event name`);
+      throw new Error(`"${String(ev)}" is a reserved event name`);
     }
     // set up packet object
     const data = [ev, ...args];
@@ -149,14 +212,65 @@ export class BroadcastOperator<EmitEvents extends EventsMap, SocketData>
       data: data,
     };
 
-    if ("function" == typeof data[data.length - 1]) {
-      throw new Error("Callbacks are not supported when broadcasting");
+    const withAck = typeof data[data.length - 1] === "function";
+
+    if (!withAck) {
+      this.adapter.broadcast(packet, {
+        rooms: this.rooms,
+        except: this.exceptRooms,
+        flags: this.flags,
+      });
+
+      return true;
     }
 
-    this.adapter.broadcast(packet, {
-      rooms: this.rooms,
-      except: this.exceptRooms,
-      flags: this.flags,
+    const ack = data.pop() as (...args: any[]) => void;
+    let timedOut = false;
+    let responses: any[] = [];
+
+    const timer = setTimeout(() => {
+      timedOut = true;
+      ack.apply(this, [new Error("operation has timed out"), responses]);
+    }, this.flags.timeout);
+
+    let expectedServerCount = -1;
+    let actualServerCount = 0;
+    let expectedClientCount = 0;
+
+    const checkCompleteness = () => {
+      if (
+        !timedOut &&
+        expectedServerCount === actualServerCount &&
+        responses.length === expectedClientCount
+      ) {
+        clearTimeout(timer);
+        ack.apply(this, [null, responses]);
+      }
+    };
+
+    this.adapter.broadcastWithAck(
+      packet,
+      {
+        rooms: this.rooms,
+        except: this.exceptRooms,
+        flags: this.flags,
+      },
+      (clientCount) => {
+        // each Socket.IO server in the cluster sends the number of clients that were notified
+        expectedClientCount += clientCount;
+        actualServerCount++;
+        checkCompleteness();
+      },
+      (clientResponse) => {
+        // each client sends an acknowledgement
+        responses.push(clientResponse);
+        checkCompleteness();
+      }
+    );
+
+    this.adapter.serverCount().then((serverCount) => {
+      expectedServerCount = serverCount;
+      checkCompleteness();
     });
 
     return true;
@@ -165,7 +279,8 @@ export class BroadcastOperator<EmitEvents extends EventsMap, SocketData>
   /**
    * Gets a list of clients.
    *
-   * @public
+   * @deprecated this method will be removed in the next major release, please use {@link Server#serverSideEmit} or
+   * {@link fetchSockets} instead.
    */
   public allSockets(): Promise<Set<SocketId>> {
     if (!this.adapter) {
@@ -177,17 +292,35 @@ export class BroadcastOperator<EmitEvents extends EventsMap, SocketData>
   }
 
   /**
-   * Returns the matching socket instances
+   * Returns the matching socket instances. This method works across a cluster of several Socket.IO servers.
    *
-   * @public
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   * // return all Socket instances
+   * const sockets = await io.fetchSockets();
+   *
+   * // return all Socket instances in the "room1" room
+   * const sockets = await io.in("room1").fetchSockets();
+   *
+   * for (const socket of sockets) {
+   *   console.log(socket.id);
+   *   console.log(socket.handshake);
+   *   console.log(socket.rooms);
+   *   console.log(socket.data);
+   *
+   *   socket.emit("hello");
+   *   socket.join("room1");
+   *   socket.leave("room2");
+   *   socket.disconnect();
+   * }
    */
-  public fetchSockets<SocketData = any>(): Promise<
-    RemoteSocket<EmitEvents, SocketData>[]
-  > {
+  public fetchSockets(): Promise<RemoteSocket<EmitEvents, SocketData>[]> {
     return this.adapter
       .fetchSockets({
         rooms: this.rooms,
         except: this.exceptRooms,
+        flags: this.flags,
       })
       .then((sockets) => {
         return sockets.map((socket) => {
@@ -205,48 +338,76 @@ export class BroadcastOperator<EmitEvents extends EventsMap, SocketData>
   }
 
   /**
-   * Makes the matching socket instances join the specified rooms
+   * Makes the matching socket instances join the specified rooms.
    *
-   * @param room
-   * @public
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   *
+   * // make all socket instances join the "room1" room
+   * io.socketsJoin("room1");
+   *
+   * // make all socket instances in the "room1" room join the "room2" and "room3" rooms
+   * io.in("room1").socketsJoin(["room2", "room3"]);
+   *
+   * @param room - a room, or an array of rooms
    */
   public socketsJoin(room: Room | Room[]): void {
     this.adapter.addSockets(
       {
         rooms: this.rooms,
         except: this.exceptRooms,
+        flags: this.flags,
       },
       Array.isArray(room) ? room : [room]
     );
   }
 
   /**
-   * Makes the matching socket instances leave the specified rooms
+   * Makes the matching socket instances leave the specified rooms.
    *
-   * @param room
-   * @public
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   * // make all socket instances leave the "room1" room
+   * io.socketsLeave("room1");
+   *
+   * // make all socket instances in the "room1" room leave the "room2" and "room3" rooms
+   * io.in("room1").socketsLeave(["room2", "room3"]);
+   *
+   * @param room - a room, or an array of rooms
    */
   public socketsLeave(room: Room | Room[]): void {
     this.adapter.delSockets(
       {
         rooms: this.rooms,
         except: this.exceptRooms,
+        flags: this.flags,
       },
       Array.isArray(room) ? room : [room]
     );
   }
 
   /**
-   * Makes the matching socket instances disconnect
+   * Makes the matching socket instances disconnect.
+   *
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   * // make all socket instances disconnect (the connections might be kept alive for other namespaces)
+   * io.disconnectSockets();
+   *
+   * // make all socket instances in the "room1" room disconnect and close the underlying connections
+   * io.in("room1").disconnectSockets(true);
    *
    * @param close - whether to close the underlying connection
-   * @public
    */
   public disconnectSockets(close: boolean = false): void {
     this.adapter.disconnectSockets(
       {
         rooms: this.rooms,
         except: this.exceptRooms,
+        flags: this.flags,
       },
       close
     );
@@ -281,7 +442,10 @@ export class RemoteSocket<EmitEvents extends EventsMap, SocketData>
     this.handshake = details.handshake;
     this.rooms = new Set(details.rooms);
     this.data = details.data;
-    this.operator = new BroadcastOperator(adapter, new Set([this.id]));
+    this.operator = new BroadcastOperator<EmitEvents, SocketData>(
+      adapter,
+      new Set([this.id])
+    );
   }
 
   public emit<Ev extends EventNames<EmitEvents>>(
@@ -295,7 +459,6 @@ export class RemoteSocket<EmitEvents extends EventsMap, SocketData>
    * Joins a room.
    *
    * @param {String|Array} room - room or array of rooms
-   * @public
    */
   public join(room: Room | Room[]): void {
     return this.operator.socketsJoin(room);
@@ -305,7 +468,6 @@ export class RemoteSocket<EmitEvents extends EventsMap, SocketData>
    * Leaves a room.
    *
    * @param {String} room
-   * @public
    */
   public leave(room: Room): void {
     return this.operator.socketsLeave(room);
@@ -316,8 +478,6 @@ export class RemoteSocket<EmitEvents extends EventsMap, SocketData>
    *
    * @param {Boolean} close - if `true`, closes the underlying connection
    * @return {Socket} self
-   *
-   * @public
    */
   public disconnect(close = false): this {
     this.operator.disconnectSockets(close);

lib/client.ts

@@ -18,6 +18,13 @@ interface WriteOptions {
   wsPreEncoded?: string;
 }
 
+type CloseReason =
+  | "transport error"
+  | "transport close"
+  | "forced close"
+  | "ping timeout"
+  | "parse error";
+
 export class Client<
   ListenEvents extends EventsMap,
   EmitEvents extends EventsMap,
@@ -248,6 +255,7 @@ export class Client<
     try {
       this.decoder.add(data);
     } catch (e) {
+      debug("invalid packet format");
       this.onerror(e);
     }
   }
@@ -258,22 +266,31 @@ export class Client<
    * @private
    */
   private ondecoded(packet: Packet): void {
-    if (PacketType.CONNECT === packet.type) {
-      if (this.conn.protocol === 3) {
-        const parsed = url.parse(packet.nsp, true);
-        this.connect(parsed.pathname!, parsed.query);
-      } else {
-        this.connect(packet.nsp, packet.data);
-      }
+    let namespace: string;
+    let authPayload;
+    if (this.conn.protocol === 3) {
+      const parsed = url.parse(packet.nsp, true);
+      namespace = parsed.pathname!;
+      authPayload = parsed.query;
     } else {
-      const socket = this.nsps.get(packet.nsp);
-      if (socket) {
-        process.nextTick(function () {
-          socket._onpacket(packet);
-        });
-      } else {
-        debug("no socket for namespace %s", packet.nsp);
-      }
+      namespace = packet.nsp;
+      authPayload = packet.data;
+    }
+    const socket = this.nsps.get(namespace);
+
+    if (!socket && packet.type === PacketType.CONNECT) {
+      this.connect(namespace, authPayload);
+    } else if (
+      socket &&
+      packet.type !== PacketType.CONNECT &&
+      packet.type !== PacketType.CONNECT_ERROR
+    ) {
+      process.nextTick(function () {
+        socket._onpacket(packet);
+      });
+    } else {
+      debug("invalid state (packet type: %s)", packet.type);
+      this.close();
     }
   }
 
@@ -296,7 +313,7 @@ export class Client<
    * @param reason
    * @private
    */
-  private onclose(reason: string): void {
+  private onclose(reason: CloseReason | "forced server close"): void {
     debug("client close with reason %s", reason);
 
     // ignore a potential subsequent `close` event

lib/index.ts

@@ -1,4 +1,6 @@
 import http = require("http");
+import type { Server as HTTPSServer } from "https";
+import type { Http2SecureServer } from "http2";
 import { createReadStream } from "fs";
 import { createDeflate, createGzip, createBrotliCompress } from "zlib";
 import accepts = require("accepts");
@@ -28,7 +30,7 @@ import {
   StrictEventEmitter,
   EventNames,
 } from "./typed-events";
-import { patchAdapter, restoreAdapter, serveFile } from "./uws.js";
+import { patchAdapter, restoreAdapter, serveFile } from "./uws";
 
 const debug = debugModule("socket.io:server");
 
@@ -71,6 +73,32 @@ interface ServerOptions extends EngineOptions, AttachOptions {
   connectTimeout: number;
 }
 
+/**
+ * Represents a Socket.IO server.
+ *
+ * @example
+ * import { Server } from "socket.io";
+ *
+ * const io = new Server();
+ *
+ * io.on("connection", (socket) => {
+ *   console.log(`socket ${socket.id} connected`);
+ *
+ *   // send an event to the client
+ *   socket.emit("foo", "bar");
+ *
+ *   socket.on("foobar", () => {
+ *     // an event was received from the client
+ *   });
+ *
+ *   // upon disconnection
+ *   socket.on("disconnect", (reason) => {
+ *     console.log(`socket ${socket.id} disconnected due to ${reason}`);
+ *   });
+ * });
+ *
+ * io.listen(3000);
+ */
 export class Server<
   ListenEvents extends EventsMap = DefaultEventsMap,
   EmitEvents extends EventsMap = ListenEvents,
@@ -95,11 +123,8 @@ export class Server<
   /**
    * A reference to the underlying Engine.IO server.
    *
-   * Example:
-   *
-   * <code>
-   *   const clientsCount = io.engine.clientsCount;
-   * </code>
+   * @example
+   * const clientsCount = io.engine.clientsCount;
    *
    */
   public engine: any;
@@ -131,23 +156,37 @@ export class Server<
    * @private
    */
   _connectTimeout: number;
-  private httpServer: http.Server;
+  private httpServer: http.Server | HTTPSServer | Http2SecureServer;
 
   /**
    * Server constructor.
    *
    * @param srv http server, port, or options
    * @param [opts]
-   * @public
    */
   constructor(opts?: Partial<ServerOptions>);
-  constructor(srv?: http.Server | number, opts?: Partial<ServerOptions>);
   constructor(
-    srv: undefined | Partial<ServerOptions> | http.Server | number,
+    srv?: http.Server | HTTPSServer | Http2SecureServer | number,
     opts?: Partial<ServerOptions>
   );
   constructor(
-    srv: undefined | Partial<ServerOptions> | http.Server | number,
+    srv:
+      | undefined
+      | Partial<ServerOptions>
+      | http.Server
+      | HTTPSServer
+      | Http2SecureServer
+      | number,
+    opts?: Partial<ServerOptions>
+  );
+  constructor(
+    srv:
+      | undefined
+      | Partial<ServerOptions>
+      | http.Server
+      | HTTPSServer
+      | Http2SecureServer
+      | number,
     opts: Partial<ServerOptions> = {}
   ) {
     super();
@@ -167,7 +206,10 @@ export class Server<
     this.adapter(opts.adapter || Adapter);
     this.sockets = this.of("/");
     this.opts = opts;
-    if (srv || typeof srv == "number") this.attach(srv as http.Server | number);
+    if (srv || typeof srv == "number")
+      this.attach(
+        srv as http.Server | HTTPSServer | Http2SecureServer | number
+      );
   }
 
   /**
@@ -175,7 +217,6 @@ export class Server<
    *
    * @param v - whether to serve client code
    * @return self when setting or value when getting
-   * @public
    */
   public serveClient(v: boolean): this;
   public serveClient(): boolean;
@@ -238,7 +279,6 @@ export class Server<
    *
    * @param {String} v pathname
    * @return {Server|String} self when setting or value when getting
-   * @public
    */
   public path(v: string): this;
   public path(): string;
@@ -260,7 +300,6 @@ export class Server<
   /**
    * Set the delay after which a client without namespace is closed
    * @param v
-   * @public
    */
   public connectTimeout(v: number): this;
   public connectTimeout(): number;
@@ -276,7 +315,6 @@ export class Server<
    *
    * @param v pathname
    * @return self when setting or value when getting
-   * @public
    */
   public adapter(): AdapterConstructor | undefined;
   public adapter(v: AdapterConstructor): this;
@@ -297,10 +335,9 @@ export class Server<
    * @param srv - server or port
    * @param opts - options passed to engine.io
    * @return self
-   * @public
    */
   public listen(
-    srv: http.Server | number,
+    srv: http.Server | HTTPSServer | Http2SecureServer | number,
     opts: Partial<ServerOptions> = {}
   ): this {
     return this.attach(srv, opts);
@@ -312,10 +349,9 @@ export class Server<
    * @param srv - server or port
    * @param opts - options passed to engine.io
    * @return self
-   * @public
    */
   public attach(
-    srv: http.Server | number,
+    srv: http.Server | HTTPSServer | Http2SecureServer | number,
     opts: Partial<ServerOptions> = {}
   ): this {
     if ("function" == typeof srv) {
@@ -421,7 +457,7 @@ export class Server<
    * @private
    */
   private initEngine(
-    srv: http.Server,
+    srv: http.Server | HTTPSServer | Http2SecureServer,
     opts: EngineOptions & AttachOptions
   ): void {
     // initialize engine
@@ -444,7 +480,9 @@ export class Server<
    * @param srv http server
    * @private
    */
-  private attachServe(srv: http.Server): void {
+  private attachServe(
+    srv: http.Server | HTTPSServer | Http2SecureServer
+  ): void {
     debug("attaching client serving req handler");
 
     const evs = srv.listeners("request").slice(0);
@@ -546,7 +584,6 @@ export class Server<
    *
    * @param {engine.Server} engine engine.io (or compatible) server
    * @return self
-   * @public
    */
   public bind(engine): this {
     this.engine = engine;
@@ -574,9 +611,20 @@ export class Server<
   /**
    * Looks up a namespace.
    *
-   * @param {String|RegExp|Function} name nsp name
+   * @example
+   * // with a simple string
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * // with a regex
+   * const dynamicNsp = io.of(/^\/dynamic-\d+$/).on("connection", (socket) => {
+   *   const namespace = socket.nsp; // newNamespace.name === "/dynamic-101"
+   *
+   *   // broadcast to all clients in the given sub-namespace
+   *   namespace.emit("hello");
+   * });
+   *
+   * @param name - nsp name
    * @param fn optional, nsp `connection` ev handler
-   * @public
    */
   public of(
     name: string | RegExp | ParentNspNameMatchFn,
@@ -622,7 +670,6 @@ export class Server<
    * Closes server connection
    *
    * @param [fn] optional, called as `fn([err])` on error OR all conns closed
-   * @public
    */
   public close(fn?: (err?: Error) => void): void {
     for (const socket of this.sockets.sockets.values()) {
@@ -642,10 +689,15 @@ export class Server<
   }
 
   /**
-   * Sets up namespace middleware.
+   * Registers a middleware, which is a function that gets executed for every incoming {@link Socket}.
    *
-   * @return self
-   * @public
+   * @example
+   * io.use((socket, next) => {
+   *   // ...
+   *   next();
+   * });
+   *
+   * @param fn - the middleware function
    */
   public use(
     fn: (
@@ -660,43 +712,71 @@ export class Server<
   /**
    * Targets a room when emitting.
    *
-   * @param room
-   * @return self
-   * @public
+   * @example
+   * // the “foo” event will be broadcast to all connected clients in the “room-101” room
+   * io.to("room-101").emit("foo", "bar");
+   *
+   * // with an array of rooms (a client will be notified at most once)
+   * io.to(["room-101", "room-102"]).emit("foo", "bar");
+   *
+   * // with multiple chained calls
+   * io.to("room-101").to("room-102").emit("foo", "bar");
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public to(room: Room | Room[]): BroadcastOperator<EmitEvents, SocketData> {
+  public to(room: Room | Room[]) {
     return this.sockets.to(room);
   }
 
   /**
-   * Targets a room when emitting.
+   * Targets a room when emitting. Similar to `to()`, but might feel clearer in some cases:
    *
-   * @param room
-   * @return self
-   * @public
+   * @example
+   * // disconnect all clients in the "room-101" room
+   * io.in("room-101").disconnectSockets();
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public in(room: Room | Room[]): BroadcastOperator<EmitEvents, SocketData> {
+  public in(room: Room | Room[]) {
     return this.sockets.in(room);
   }
 
   /**
    * Excludes a room when emitting.
    *
-   * @param name
-   * @return self
-   * @public
+   * @example
+   * // the "foo" event will be broadcast to all connected clients, except the ones that are in the "room-101" room
+   * io.except("room-101").emit("foo", "bar");
+   *
+   * // with an array of rooms
+   * io.except(["room-101", "room-102"]).emit("foo", "bar");
+   *
+   * // with multiple chained calls
+   * io.except("room-101").except("room-102").emit("foo", "bar");
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public except(
-    name: Room | Room[]
-  ): BroadcastOperator<EmitEvents, SocketData> {
-    return this.sockets.except(name);
+  public except(room: Room | Room[]) {
+    return this.sockets.except(room);
   }
 
   /**
    * Sends a `message` event to all clients.
    *
+   * This method mimics the WebSocket.send() method.
+   *
+   * @see https://developer.mozilla.org/en-US/docs/Web/API/WebSocket/send
+   *
+   * @example
+   * io.send("hello");
+   *
+   * // this is equivalent to
+   * io.emit("message", "hello");
+   *
    * @return self
-   * @public
    */
   public send(...args: EventParams<EmitEvents, "message">): this {
     this.sockets.emit("message", ...args);
@@ -704,10 +784,9 @@ export class Server<
   }
 
   /**
-   * Sends a `message` event to all clients.
+   * Sends a `message` event to all clients. Alias of {@link send}.
    *
    * @return self
-   * @public
    */
   public write(...args: EventParams<EmitEvents, "message">): this {
     this.sockets.emit("message", ...args);
@@ -715,11 +794,30 @@ export class Server<
   }
 
   /**
-   * Emit a packet to other Socket.IO servers
+   * Sends a message to the other Socket.IO servers of the cluster.
+   *
+   * @example
+   * io.serverSideEmit("hello", "world");
+   *
+   * io.on("hello", (arg1) => {
+   *   console.log(arg1); // prints "world"
+   * });
+   *
+   * // acknowledgements (without binary content) are supported too:
+   * io.serverSideEmit("ping", (err, responses) => {
+   *  if (err) {
+   *     // some clients did not acknowledge the event in the given delay
+   *   } else {
+   *     console.log(responses); // one response per client
+   *   }
+   * });
+   *
+   * io.on("ping", (cb) => {
+   *   cb("pong");
+   * });
    *
    * @param ev - the event name
    * @param args - an array of arguments, which may include an acknowledgement callback at the end
-   * @public
    */
   public serverSideEmit<Ev extends EventNames<ServerSideEvents>>(
     ev: Ev,
@@ -731,7 +829,8 @@ export class Server<
   /**
    * Gets a list of socket ids.
    *
-   * @public
+   * @deprecated this method will be removed in the next major release, please use {@link Server#serverSideEmit} or
+   * {@link Server#fetchSockets} instead.
    */
   public allSockets(): Promise<Set<SocketId>> {
     return this.sockets.allSockets();
@@ -740,13 +839,13 @@ export class Server<
   /**
    * Sets the compress flag.
    *
+   * @example
+   * io.compress(false).emit("hello");
+   *
    * @param compress - if `true`, compresses the sending data
-   * @return self
-   * @public
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public compress(
-    compress: boolean
-  ): BroadcastOperator<EmitEvents, SocketData> {
+  public compress(compress: boolean) {
     return this.sockets.compress(compress);
   }
 
@@ -755,59 +854,126 @@ export class Server<
    * receive messages (because of network slowness or other issues, or because they’re connected through long polling
    * and is in the middle of a request-response cycle).
    *
-   * @return self
-   * @public
+   * @example
+   * io.volatile.emit("hello"); // the clients may or may not receive it
+   *
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public get volatile(): BroadcastOperator<EmitEvents, SocketData> {
+  public get volatile() {
     return this.sockets.volatile;
   }
 
   /**
    * Sets a modifier for a subsequent event emission that the event data will only be broadcast to the current node.
    *
-   * @return self
-   * @public
+   * @example
+   * // the “foo” event will be broadcast to all connected clients on this node
+   * io.local.emit("foo", "bar");
+   *
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public get local(): BroadcastOperator<EmitEvents, SocketData> {
+  public get local() {
     return this.sockets.local;
   }
 
   /**
-   * Returns the matching socket instances
+   * Adds a timeout in milliseconds for the next operation.
    *
-   * @public
+   * @example
+   * io.timeout(1000).emit("some-event", (err, responses) => {
+   *   if (err) {
+   *     // some clients did not acknowledge the event in the given delay
+   *   } else {
+   *     console.log(responses); // one response per client
+   *   }
+   * });
+   *
+   * @param timeout
+   */
+  public timeout(timeout: number) {
+    return this.sockets.timeout(timeout);
+  }
+
+  /**
+   * Returns the matching socket instances.
+   *
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   * // return all Socket instances
+   * const sockets = await io.fetchSockets();
+   *
+   * // return all Socket instances in the "room1" room
+   * const sockets = await io.in("room1").fetchSockets();
+   *
+   * for (const socket of sockets) {
+   *   console.log(socket.id);
+   *   console.log(socket.handshake);
+   *   console.log(socket.rooms);
+   *   console.log(socket.data);
+   *
+   *   socket.emit("hello");
+   *   socket.join("room1");
+   *   socket.leave("room2");
+   *   socket.disconnect();
+   * }
    */
   public fetchSockets(): Promise<RemoteSocket<EmitEvents, SocketData>[]> {
     return this.sockets.fetchSockets();
   }
 
   /**
-   * Makes the matching socket instances join the specified rooms
+   * Makes the matching socket instances join the specified rooms.
    *
-   * @param room
-   * @public
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   *
+   * // make all socket instances join the "room1" room
+   * io.socketsJoin("room1");
+   *
+   * // make all socket instances in the "room1" room join the "room2" and "room3" rooms
+   * io.in("room1").socketsJoin(["room2", "room3"]);
+   *
+   * @param room - a room, or an array of rooms
    */
-  public socketsJoin(room: Room | Room[]): void {
+  public socketsJoin(room: Room | Room[]) {
     return this.sockets.socketsJoin(room);
   }
 
   /**
-   * Makes the matching socket instances leave the specified rooms
+   * Makes the matching socket instances leave the specified rooms.
    *
-   * @param room
-   * @public
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   * // make all socket instances leave the "room1" room
+   * io.socketsLeave("room1");
+   *
+   * // make all socket instances in the "room1" room leave the "room2" and "room3" rooms
+   * io.in("room1").socketsLeave(["room2", "room3"]);
+   *
+   * @param room - a room, or an array of rooms
    */
-  public socketsLeave(room: Room | Room[]): void {
+  public socketsLeave(room: Room | Room[]) {
     return this.sockets.socketsLeave(room);
   }
 
   /**
-   * Makes the matching socket instances disconnect
+   * Makes the matching socket instances disconnect.
+   *
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   * // make all socket instances disconnect (the connections might be kept alive for other namespaces)
+   * io.disconnectSockets();
+   *
+   * // make all socket instances in the "room1" room disconnect and close the underlying connections
+   * io.in("room1").disconnectSockets(true);
    *
    * @param close - whether to close the underlying connection
-   * @public
    */
-  public disconnectSockets(close: boolean = false): void {
+  public disconnectSockets(close: boolean = false) {
     return this.sockets.disconnectSockets(close);
   }
 }

lib/namespace.ts

@@ -33,9 +33,9 @@ export interface NamespaceReservedEventsMap<
 }
 
 export interface ServerReservedEventsMap<
-  ListenEvents,
-  EmitEvents,
-  ServerSideEvents,
+  ListenEvents extends EventsMap,
+  EmitEvents extends EventsMap,
+  ServerSideEvents extends EventsMap,
   SocketData
 > extends NamespaceReservedEventsMap<
     ListenEvents,
@@ -52,6 +52,59 @@ export const RESERVED_EVENTS: ReadonlySet<string | Symbol> = new Set<
   keyof ServerReservedEventsMap<never, never, never, never>
 >(<const>["connect", "connection", "new_namespace"]);
 
+/**
+ * A Namespace is a communication channel that allows you to split the logic of your application over a single shared
+ * connection.
+ *
+ * Each namespace has its own:
+ *
+ * - event handlers
+ *
+ * ```
+ * io.of("/orders").on("connection", (socket) => {
+ *   socket.on("order:list", () => {});
+ *   socket.on("order:create", () => {});
+ * });
+ *
+ * io.of("/users").on("connection", (socket) => {
+ *   socket.on("user:list", () => {});
+ * });
+ * ```
+ *
+ * - rooms
+ *
+ * ```
+ * const orderNamespace = io.of("/orders");
+ *
+ * orderNamespace.on("connection", (socket) => {
+ *   socket.join("room1");
+ *   orderNamespace.to("room1").emit("hello");
+ * });
+ *
+ * const userNamespace = io.of("/users");
+ *
+ * userNamespace.on("connection", (socket) => {
+ *   socket.join("room1"); // distinct from the room in the "orders" namespace
+ *   userNamespace.to("room1").emit("holà");
+ * });
+ * ```
+ *
+ * - middlewares
+ *
+ * ```
+ * const orderNamespace = io.of("/orders");
+ *
+ * orderNamespace.use((socket, next) => {
+ *   // ensure the socket has access to the "orders" namespace
+ * });
+ *
+ * const userNamespace = io.of("/users");
+ *
+ * userNamespace.use((socket, next) => {
+ *   // ensure the socket has access to the "users" namespace
+ * });
+ * ```
+ */
 export class Namespace<
   ListenEvents extends EventsMap = DefaultEventsMap,
   EmitEvents extends EventsMap = ListenEvents,
@@ -123,10 +176,17 @@ export class Namespace<
   }
 
   /**
-   * Sets up namespace middleware.
+   * Registers a middleware, which is a function that gets executed for every incoming {@link Socket}.
    *
-   * @return self
-   * @public
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * myNamespace.use((socket, next) => {
+   *   // ...
+   *   next();
+   * });
+   *
+   * @param fn - the middleware function
    */
   public use(
     fn: (
@@ -171,36 +231,63 @@ export class Namespace<
   /**
    * Targets a room when emitting.
    *
-   * @param room
-   * @return self
-   * @public
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * // the “foo” event will be broadcast to all connected clients in the “room-101” room
+   * myNamespace.to("room-101").emit("foo", "bar");
+   *
+   * // with an array of rooms (a client will be notified at most once)
+   * myNamespace.to(["room-101", "room-102"]).emit("foo", "bar");
+   *
+   * // with multiple chained calls
+   * myNamespace.to("room-101").to("room-102").emit("foo", "bar");
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public to(room: Room | Room[]): BroadcastOperator<EmitEvents, SocketData> {
-    return new BroadcastOperator(this.adapter).to(room);
+  public to(room: Room | Room[]) {
+    return new BroadcastOperator<EmitEvents, SocketData>(this.adapter).to(room);
   }
 
   /**
-   * Targets a room when emitting.
+   * Targets a room when emitting. Similar to `to()`, but might feel clearer in some cases:
    *
-   * @param room
-   * @return self
-   * @public
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * // disconnect all clients in the "room-101" room
+   * myNamespace.in("room-101").disconnectSockets();
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public in(room: Room | Room[]): BroadcastOperator<EmitEvents, SocketData> {
-    return new BroadcastOperator(this.adapter).in(room);
+  public in(room: Room | Room[]) {
+    return new BroadcastOperator<EmitEvents, SocketData>(this.adapter).in(room);
   }
 
   /**
    * Excludes a room when emitting.
    *
-   * @param room
-   * @return self
-   * @public
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * // the "foo" event will be broadcast to all connected clients, except the ones that are in the "room-101" room
+   * myNamespace.except("room-101").emit("foo", "bar");
+   *
+   * // with an array of rooms
+   * myNamespace.except(["room-101", "room-102"]).emit("foo", "bar");
+   *
+   * // with multiple chained calls
+   * myNamespace.except("room-101").except("room-102").emit("foo", "bar");
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public except(
-    room: Room | Room[]
-  ): BroadcastOperator<EmitEvents, SocketData> {
-    return new BroadcastOperator(this.adapter).except(room);
+  public except(room: Room | Room[]) {
+    return new BroadcastOperator<EmitEvents, SocketData>(this.adapter).except(
+      room
+    );
   }
 
   /**
@@ -218,34 +305,38 @@ export class Namespace<
     const socket = new Socket(this, client, query);
     this.run(socket, (err) => {
       process.nextTick(() => {
-        if ("open" == client.conn.readyState) {
-          if (err) {
-            if (client.conn.protocol === 3) {
-              return socket._error(err.data || err.message);
-            } else {
-              return socket._error({
-                message: err.message,
-                data: err.data,
-              });
-            }
-          }
-
-          // track socket
-          this.sockets.set(socket.id, socket);
-
-          // it's paramount that the internal `onconnect` logic
-          // fires before user-set events to prevent state order
-          // violations (such as a disconnection before the connection
-          // logic is complete)
-          socket._onconnect();
-          if (fn) fn();
-
-          // fire user-set events
-          this.emitReserved("connect", socket);
-          this.emitReserved("connection", socket);
-        } else {
+        if ("open" !== client.conn.readyState) {
           debug("next called after client was closed - ignoring socket");
+          socket._cleanup();
+          return;
         }
+
+        if (err) {
+          debug("middleware error, sending CONNECT_ERROR packet to the client");
+          socket._cleanup();
+          if (client.conn.protocol === 3) {
+            return socket._error(err.data || err.message);
+          } else {
+            return socket._error({
+              message: err.message,
+              data: err.data,
+            });
+          }
+        }
+
+        // track socket
+        this.sockets.set(socket.id, socket);
+
+        // it's paramount that the internal `onconnect` logic
+        // fires before user-set events to prevent state order
+        // violations (such as a disconnection before the connection
+        // logic is complete)
+        socket._onconnect();
+        if (fn) fn();
+
+        // fire user-set events
+        this.emitReserved("connect", socket);
+        this.emitReserved("connection", socket);
       });
     });
     return socket;
@@ -267,10 +358,26 @@ export class Namespace<
   }
 
   /**
-   * Emits to all clients.
+   * Emits to all connected clients.
+   *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * myNamespace.emit("hello", "world");
+   *
+   * // all serializable datastructures are supported (no need to call JSON.stringify)
+   * myNamespace.emit("hello", 1, "2", { 3: ["4"], 5: Uint8Array.from([6]) });
+   *
+   * // with an acknowledgement from the clients
+   * myNamespace.timeout(1000).emit("some-event", (err, responses) => {
+   *   if (err) {
+   *     // some clients did not acknowledge the event in the given delay
+   *   } else {
+   *     console.log(responses); // one response per client
+   *   }
+   * });
    *
    * @return Always true
-   * @public
    */
   public emit<Ev extends EventNames<EmitEvents>>(
     ev: Ev,
@@ -285,8 +392,19 @@ export class Namespace<
   /**
    * Sends a `message` event to all clients.
    *
+   * This method mimics the WebSocket.send() method.
+   *
+   * @see https://developer.mozilla.org/en-US/docs/Web/API/WebSocket/send
+   *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * myNamespace.send("hello");
+   *
+   * // this is equivalent to
+   * myNamespace.emit("message", "hello");
+   *
    * @return self
-   * @public
    */
   public send(...args: EventParams<EmitEvents, "message">): this {
     this.emit("message", ...args);
@@ -294,10 +412,9 @@ export class Namespace<
   }
 
   /**
-   * Sends a `message` event to all clients.
+   * Sends a `message` event to all clients. Sends a `message` event. Alias of {@link send}.
    *
    * @return self
-   * @public
    */
   public write(...args: EventParams<EmitEvents, "message">): this {
     this.emit("message", ...args);
@@ -305,18 +422,39 @@ export class Namespace<
   }
 
   /**
-   * Emit a packet to other Socket.IO servers
+   * Sends a message to the other Socket.IO servers of the cluster.
+   *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * myNamespace.serverSideEmit("hello", "world");
+   *
+   * myNamespace.on("hello", (arg1) => {
+   *   console.log(arg1); // prints "world"
+   * });
+   *
+   * // acknowledgements (without binary content) are supported too:
+   * myNamespace.serverSideEmit("ping", (err, responses) => {
+   *  if (err) {
+   *     // some clients did not acknowledge the event in the given delay
+   *   } else {
+   *     console.log(responses); // one response per client
+   *   }
+   * });
+   *
+   * myNamespace.on("ping", (cb) => {
+   *   cb("pong");
+   * });
    *
    * @param ev - the event name
    * @param args - an array of arguments, which may include an acknowledgement callback at the end
-   * @public
    */
   public serverSideEmit<Ev extends EventNames<ServerSideEvents>>(
     ev: Ev,
     ...args: EventParams<ServerSideEvents, Ev>
   ): boolean {
     if (RESERVED_EVENTS.has(ev)) {
-      throw new Error(`"${ev}" is a reserved event name`);
+      throw new Error(`"${String(ev)}" is a reserved event name`);
     }
     args.unshift(ev);
     this.adapter.serverSideEmit(args);
@@ -337,24 +475,30 @@ export class Namespace<
   /**
    * Gets a list of clients.
    *
-   * @return self
-   * @public
+   * @deprecated this method will be removed in the next major release, please use {@link Namespace#serverSideEmit} or
+   * {@link Namespace#fetchSockets} instead.
    */
   public allSockets(): Promise<Set<SocketId>> {
-    return new BroadcastOperator(this.adapter).allSockets();
+    return new BroadcastOperator<EmitEvents, SocketData>(
+      this.adapter
+    ).allSockets();
   }
 
   /**
    * Sets the compress flag.
    *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * myNamespace.compress(false).emit("hello");
+   *
    * @param compress - if `true`, compresses the sending data
    * @return self
-   * @public
    */
-  public compress(
-    compress: boolean
-  ): BroadcastOperator<EmitEvents, SocketData> {
-    return new BroadcastOperator(this.adapter).compress(compress);
+  public compress(compress: boolean) {
+    return new BroadcastOperator<EmitEvents, SocketData>(this.adapter).compress(
+      compress
+    );
   }
 
   /**
@@ -362,59 +506,149 @@ export class Namespace<
    * receive messages (because of network slowness or other issues, or because they’re connected through long polling
    * and is in the middle of a request-response cycle).
    *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * myNamespace.volatile.emit("hello"); // the clients may or may not receive it
+   *
    * @return self
-   * @public
    */
-  public get volatile(): BroadcastOperator<EmitEvents, SocketData> {
-    return new BroadcastOperator(this.adapter).volatile;
+  public get volatile() {
+    return new BroadcastOperator<EmitEvents, SocketData>(this.adapter).volatile;
   }
 
   /**
    * Sets a modifier for a subsequent event emission that the event data will only be broadcast to the current node.
    *
-   * @return self
-   * @public
-   */
-  public get local(): BroadcastOperator<EmitEvents, SocketData> {
-    return new BroadcastOperator(this.adapter).local;
-  }
-
-  /**
-   * Returns the matching socket instances
+   * @example
+   * const myNamespace = io.of("/my-namespace");
    *
-   * @public
-   */
-  public fetchSockets(): Promise<RemoteSocket<EmitEvents, SocketData>[]> {
-    return new BroadcastOperator(this.adapter).fetchSockets();
-  }
-
-  /**
-   * Makes the matching socket instances join the specified rooms
+   * // the “foo” event will be broadcast to all connected clients on this node
+   * myNamespace.local.emit("foo", "bar");
    *
-   * @param room
-   * @public
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public socketsJoin(room: Room | Room[]): void {
-    return new BroadcastOperator(this.adapter).socketsJoin(room);
+  public get local() {
+    return new BroadcastOperator<EmitEvents, SocketData>(this.adapter).local;
   }
 
   /**
-   * Makes the matching socket instances leave the specified rooms
+   * Adds a timeout in milliseconds for the next operation.
    *
-   * @param room
-   * @public
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * myNamespace.timeout(1000).emit("some-event", (err, responses) => {
+   *   if (err) {
+   *     // some clients did not acknowledge the event in the given delay
+   *   } else {
+   *     console.log(responses); // one response per client
+   *   }
+   * });
+   *
+   * @param timeout
    */
-  public socketsLeave(room: Room | Room[]): void {
-    return new BroadcastOperator(this.adapter).socketsLeave(room);
+  public timeout(timeout: number) {
+    return new BroadcastOperator<EmitEvents, SocketData>(this.adapter).timeout(
+      timeout
+    );
   }
 
   /**
-   * Makes the matching socket instances disconnect
+   * Returns the matching socket instances.
+   *
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * // return all Socket instances
+   * const sockets = await myNamespace.fetchSockets();
+   *
+   * // return all Socket instances in the "room1" room
+   * const sockets = await myNamespace.in("room1").fetchSockets();
+   *
+   * for (const socket of sockets) {
+   *   console.log(socket.id);
+   *   console.log(socket.handshake);
+   *   console.log(socket.rooms);
+   *   console.log(socket.data);
+   *
+   *   socket.emit("hello");
+   *   socket.join("room1");
+   *   socket.leave("room2");
+   *   socket.disconnect();
+   * }
+   */
+  public fetchSockets() {
+    return new BroadcastOperator<EmitEvents, SocketData>(
+      this.adapter
+    ).fetchSockets();
+  }
+
+  /**
+   * Makes the matching socket instances join the specified rooms.
+   *
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * // make all socket instances join the "room1" room
+   * myNamespace.socketsJoin("room1");
+   *
+   * // make all socket instances in the "room1" room join the "room2" and "room3" rooms
+   * myNamespace.in("room1").socketsJoin(["room2", "room3"]);
+   *
+   * @param room - a room, or an array of rooms
+   */
+  public socketsJoin(room: Room | Room[]) {
+    return new BroadcastOperator<EmitEvents, SocketData>(
+      this.adapter
+    ).socketsJoin(room);
+  }
+
+  /**
+   * Makes the matching socket instances leave the specified rooms.
+   *
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * // make all socket instances leave the "room1" room
+   * myNamespace.socketsLeave("room1");
+   *
+   * // make all socket instances in the "room1" room leave the "room2" and "room3" rooms
+   * myNamespace.in("room1").socketsLeave(["room2", "room3"]);
+   *
+   * @param room - a room, or an array of rooms
+   */
+  public socketsLeave(room: Room | Room[]) {
+    return new BroadcastOperator<EmitEvents, SocketData>(
+      this.adapter
+    ).socketsLeave(room);
+  }
+
+  /**
+   * Makes the matching socket instances disconnect.
+   *
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * // make all socket instances disconnect (the connections might be kept alive for other namespaces)
+   * myNamespace.disconnectSockets();
+   *
+   * // make all socket instances in the "room1" room disconnect and close the underlying connections
+   * myNamespace.in("room1").disconnectSockets(true);
    *
    * @param close - whether to close the underlying connection
-   * @public
    */
-  public disconnectSockets(close: boolean = false): void {
-    return new BroadcastOperator(this.adapter).disconnectSockets(close);
+  public disconnectSockets(close: boolean = false) {
+    return new BroadcastOperator<EmitEvents, SocketData>(
+      this.adapter
+    ).disconnectSockets(close);
   }
 }

lib/socket.ts

@@ -25,9 +25,23 @@ const debug = debugModule("socket.io:socket");
 
 type ClientReservedEvents = "connect_error";
 
+// TODO for next major release: cleanup disconnect reasons
+export type DisconnectReason =
+  // Engine.IO close reasons
+  | "transport error"
+  | "transport close"
+  | "forced close"
+  | "ping timeout"
+  | "parse error"
+  // Socket.IO disconnect reasons
+  | "server shutting down"
+  | "forced server close"
+  | "client namespace disconnect"
+  | "server namespace disconnect";
+
 export interface SocketReservedEventsMap {
-  disconnect: (reason: string) => void;
-  disconnecting: (reason: string) => void;
+  disconnect: (reason: DisconnectReason) => void;
+  disconnecting: (reason: DisconnectReason) => void;
   error: (err: Error) => void;
 }
 
@@ -107,8 +121,44 @@ export interface Handshake {
   auth: { [key: string]: any };
 }
 
-export type Event = [eventName: string, ...args: any[]];
+/**
+ * `[eventName, ...args]`
+ */
+export type Event = [string, ...any[]];
 
+function noop() {}
+
+/**
+ * This is the main object for interacting with a client.
+ *
+ * A Socket belongs to a given {@link Namespace} and uses an underlying {@link Client} to communicate.
+ *
+ * Within each {@link Namespace}, you can also define arbitrary channels (called "rooms") that the {@link Socket} can
+ * join and leave. That provides a convenient way to broadcast to a group of socket instances.
+ *
+ * @example
+ * io.on("connection", (socket) => {
+ *   console.log(`socket ${socket.id} connected`);
+ *
+ *   // send an event to the client
+ *   socket.emit("foo", "bar");
+ *
+ *   socket.on("foobar", () => {
+ *     // an event was received from the client
+ *   });
+ *
+ *   // join the room named "room1"
+ *   socket.join("room1");
+ *
+ *   // broadcast to everyone in the room named "room1"
+ *   io.to("room1").emit("hello");
+ *
+ *   // upon disconnection
+ *   socket.on("disconnect", (reason) => {
+ *     console.log(`socket ${socket.id} disconnected due to ${reason}`);
+ *   });
+ * });
+ */
 export class Socket<
   ListenEvents extends EventsMap = DefaultEventsMap,
   EmitEvents extends EventsMap = ListenEvents,
@@ -119,13 +169,32 @@ export class Socket<
   EmitEvents,
   SocketReservedEventsMap
 > {
+  /**
+   * An unique identifier for the session.
+   */
   public readonly id: SocketId;
+  /**
+   * The handshake details.
+   */
   public readonly handshake: Handshake;
   /**
-   * Additional information that can be attached to the Socket instance and which will be used in the fetchSockets method
+   * Additional information that can be attached to the Socket instance and which will be used in the
+   * {@link Server.fetchSockets()} method.
    */
   public data: Partial<SocketData> = {};
-
+  /**
+   * Whether the socket is currently connected or not.
+   *
+   * @example
+   * io.use((socket, next) => {
+   *   console.log(socket.connected); // false
+   *   next();
+   * });
+   *
+   * io.on("connection", (socket) => {
+   *   console.log(socket.connected); // true
+   * });
+   */
   public connected: boolean = false;
 
   private readonly server: Server<
@@ -137,8 +206,9 @@ export class Socket<
   private readonly adapter: Adapter;
   private acks: Map<number, () => void> = new Map();
   private fns: Array<(event: Event, next: (err?: Error) => void) => void> = [];
-  private flags: BroadcastFlags & { timeout?: number } = {};
+  private flags: BroadcastFlags = {};
   private _anyListeners?: Array<(...args: any[]) => void>;
+  private _anyOutgoingListeners?: Array<(...args: any[]) => void>;
 
   /**
    * Interface to a `Client` for a given `Namespace`.
@@ -189,15 +259,27 @@ export class Socket<
   /**
    * Emits to this client.
    *
+   * @example
+   * io.on("connection", (socket) => {
+   *   socket.emit("hello", "world");
+   *
+   *   // all serializable datastructures are supported (no need to call JSON.stringify)
+   *   socket.emit("hello", 1, "2", { 3: ["4"], 5: Buffer.from([6]) });
+   *
+   *   // with an acknowledgement from the client
+   *   socket.emit("hello", "world", (val) => {
+   *     // ...
+   *   });
+   * });
+   *
    * @return Always returns `true`.
-   * @public
    */
   public emit<Ev extends EventNames<EmitEvents>>(
     ev: Ev,
     ...args: EventParams<EmitEvents, Ev>
   ): boolean {
     if (RESERVED_EVENTS.has(ev)) {
-      throw new Error(`"${ev}" is a reserved event name`);
+      throw new Error(`"${String(ev)}" is a reserved event name`);
     }
     const data: any[] = [ev, ...args];
     const packet: any = {
@@ -217,6 +299,7 @@ export class Socket<
     const flags = Object.assign({}, this.flags);
     this.flags = {};
 
+    this.notifyOutgoingListeners(packet);
     this.packet(packet, flags);
 
     return true;
@@ -247,43 +330,83 @@ export class Socket<
   /**
    * Targets a room when broadcasting.
    *
-   * @param room
-   * @return self
-   * @public
+   * @example
+   * io.on("connection", (socket) => {
+   *   // the “foo” event will be broadcast to all connected clients in the “room-101” room, except this socket
+   *   socket.to("room-101").emit("foo", "bar");
+   *
+   *   // the code above is equivalent to:
+   *   io.to("room-101").except(socket.id).emit("foo", "bar");
+   *
+   *   // with an array of rooms (a client will be notified at most once)
+   *   socket.to(["room-101", "room-102"]).emit("foo", "bar");
+   *
+   *   // with multiple chained calls
+   *   socket.to("room-101").to("room-102").emit("foo", "bar");
+   * });
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public to(room: Room | Room[]): BroadcastOperator<EmitEvents, SocketData> {
+  public to(room: Room | Room[]) {
     return this.newBroadcastOperator().to(room);
   }
 
   /**
-   * Targets a room when broadcasting.
+   * Targets a room when broadcasting. Similar to `to()`, but might feel clearer in some cases:
    *
-   * @param room
-   * @return self
-   * @public
+   * @example
+   * io.on("connection", (socket) => {
+   *   // disconnect all clients in the "room-101" room, except this socket
+   *   socket.in("room-101").disconnectSockets();
+   * });
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public in(room: Room | Room[]): BroadcastOperator<EmitEvents, SocketData> {
+  public in(room: Room | Room[]) {
     return this.newBroadcastOperator().in(room);
   }
 
   /**
    * Excludes a room when broadcasting.
    *
-   * @param room
-   * @return self
-   * @public
+   * @example
+   * io.on("connection", (socket) => {
+   *   // the "foo" event will be broadcast to all connected clients, except the ones that are in the "room-101" room
+   *   // and this socket
+   *   socket.except("room-101").emit("foo", "bar");
+   *
+   *   // with an array of rooms
+   *   socket.except(["room-101", "room-102"]).emit("foo", "bar");
+   *
+   *   // with multiple chained calls
+   *   socket.except("room-101").except("room-102").emit("foo", "bar");
+   * });
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public except(
-    room: Room | Room[]
-  ): BroadcastOperator<EmitEvents, SocketData> {
+  public except(room: Room | Room[]) {
     return this.newBroadcastOperator().except(room);
   }
 
   /**
    * Sends a `message` event.
    *
+   * This method mimics the WebSocket.send() method.
+   *
+   * @see https://developer.mozilla.org/en-US/docs/Web/API/WebSocket/send
+   *
+   * @example
+   * io.on("connection", (socket) => {
+   *   socket.send("hello");
+   *
+   *   // this is equivalent to
+   *   socket.emit("message", "hello");
+   * });
+   *
    * @return self
-   * @public
    */
   public send(...args: EventParams<EmitEvents, "message">): this {
     this.emit("message", ...args);
@@ -291,10 +414,9 @@ export class Socket<
   }
 
   /**
-   * Sends a `message` event.
+   * Sends a `message` event. Alias of {@link send}.
    *
    * @return self
-   * @public
    */
   public write(...args: EventParams<EmitEvents, "message">): this {
     this.emit("message", ...args);
@@ -320,9 +442,17 @@ export class Socket<
   /**
    * Joins a room.
    *
+   * @example
+   * io.on("connection", (socket) => {
+   *   // join a single room
+   *   socket.join("room1");
+   *
+   *   // join multiple rooms
+   *   socket.join(["room1", "room2"]);
+   * });
+   *
    * @param {String|Array} rooms - room or array of rooms
    * @return a Promise or nothing, depending on the adapter
-   * @public
    */
   public join(rooms: Room | Array<Room>): Promise<void> | void {
     debug("join room %s", rooms);
@@ -336,9 +466,17 @@ export class Socket<
   /**
    * Leaves a room.
    *
+   * @example
+   * io.on("connection", (socket) => {
+   *   // leave a single room
+   *   socket.leave("room1");
+   *
+   *   // leave multiple rooms
+   *   socket.leave("room1").leave("room2");
+   * });
+   *
    * @param {String} room
    * @return a Promise or nothing, depending on the adapter
-   * @public
    */
   public leave(room: string): Promise<void> | void {
     debug("leave room %s", room);
@@ -402,9 +540,6 @@ export class Socket<
       case PacketType.DISCONNECT:
         this.ondisconnect();
         break;
-
-      case PacketType.CONNECT_ERROR:
-        this._onerror(new Error(packet.data));
     }
   }
 
@@ -505,11 +640,11 @@ export class Socket<
    *
    * @private
    */
-  _onclose(reason: string): this | undefined {
+  _onclose(reason: DisconnectReason): this | undefined {
     if (!this.connected) return this;
     debug("closing socket - reason %s", reason);
     this.emitReserved("disconnecting", reason);
-    this.leaveAll();
+    this._cleanup();
     this.nsp._remove(this);
     this.client._remove(this);
     this.connected = false;
@@ -517,6 +652,16 @@ export class Socket<
     return;
   }
 
+  /**
+   * Makes the socket leave all the rooms it was part of and prevents it from joining any other room
+   *
+   * @private
+   */
+  _cleanup() {
+    this.leaveAll();
+    this.join = noop;
+  }
+
   /**
    * Produces an `error` packet.
    *
@@ -531,10 +676,17 @@ export class Socket<
   /**
    * Disconnects this client.
    *
-   * @param {Boolean} close - if `true`, closes the underlying connection
-   * @return {Socket} self
+   * @example
+   * io.on("connection", (socket) => {
+   *   // disconnect this socket (the connection might be kept alive for other namespaces)
+   *   socket.disconnect();
    *
-   * @public
+   *   // disconnect this socket and close the underlying connection
+   *   socket.disconnect(true);
+   * })
+   *
+   * @param {Boolean} close - if `true`, closes the underlying connection
+   * @return self
    */
   public disconnect(close = false): this {
     if (!this.connected) return this;
@@ -550,9 +702,13 @@ export class Socket<
   /**
    * Sets the compress flag.
    *
+   * @example
+   * io.on("connection", (socket) => {
+   *   socket.compress(false).emit("hello");
+   * });
+   *
    * @param {Boolean} compress - if `true`, compresses the sending data
    * @return {Socket} self
-   * @public
    */
   public compress(compress: boolean): this {
     this.flags.compress = compress;
@@ -564,8 +720,12 @@ export class Socket<
    * receive messages (because of network slowness or other issues, or because they’re connected through long polling
    * and is in the middle of a request-response cycle).
    *
+   * @example
+   * io.on("connection", (socket) => {
+   *   socket.volatile.emit("hello"); // the client may or may not receive it
+   * });
+   *
    * @return {Socket} self
-   * @public
    */
   public get volatile(): this {
     this.flags.volatile = true;
@@ -576,20 +736,30 @@ export class Socket<
    * Sets a modifier for a subsequent event emission that the event data will only be broadcast to every sockets but the
    * sender.
    *
-   * @return {Socket} self
-   * @public
+   * @example
+   * io.on("connection", (socket) => {
+   *   // the “foo” event will be broadcast to all connected clients, except this socket
+   *   socket.broadcast.emit("foo", "bar");
+   * });
+   *
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public get broadcast(): BroadcastOperator<EmitEvents, SocketData> {
+  public get broadcast() {
     return this.newBroadcastOperator();
   }
 
   /**
    * Sets a modifier for a subsequent event emission that the event data will only be broadcast to the current node.
    *
-   * @return {Socket} self
-   * @public
+   * @example
+   * io.on("connection", (socket) => {
+   *   // the “foo” event will be broadcast to all connected clients on this node, except this socket
+   *   socket.local.emit("foo", "bar");
+   * });
+   *
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public get local(): BroadcastOperator<EmitEvents, SocketData> {
+  public get local() {
     return this.newBroadcastOperator().local;
   }
 
@@ -597,16 +767,16 @@ export class Socket<
    * Sets a modifier for a subsequent event emission that the callback will be called with an error when the
    * given number of milliseconds have elapsed without an acknowledgement from the client:
    *
-   * ```
-   * socket.timeout(5000).emit("my-event", (err) => {
-   *   if (err) {
-   *     // the client did not acknowledge the event in the given delay
-   *   }
+   * @example
+   * io.on("connection", (socket) => {
+   *   socket.timeout(5000).emit("my-event", (err) => {
+   *     if (err) {
+   *       // the client did not acknowledge the event in the given delay
+   *     }
+   *   });
    * });
-   * ```
    *
    * @returns self
-   * @public
    */
   public timeout(timeout: number): this {
     this.flags.timeout = timeout;
@@ -638,9 +808,25 @@ export class Socket<
   /**
    * Sets up socket middleware.
    *
+   * @example
+   * io.on("connection", (socket) => {
+   *   socket.use(([event, ...args], next) => {
+   *     if (isUnauthorized(event)) {
+   *       return next(new Error("unauthorized event"));
+   *     }
+   *     // do not forget to call next
+   *     next();
+   *   });
+   *
+   *   socket.on("error", (err) => {
+   *     if (err && err.message === "unauthorized event") {
+   *       socket.disconnect();
+   *     }
+   *   });
+   * });
+   *
    * @param {Function} fn - middleware function (event, next)
    * @return {Socket} self
-   * @public
    */
   public use(fn: (event: Event, next: (err?: Error) => void) => void): this {
     this.fns.push(fn);
@@ -683,8 +869,6 @@ export class Socket<
 
   /**
    * A reference to the request that originated the underlying Engine.IO Socket.
-   *
-   * @public
    */
   public get request(): IncomingMessage {
     return this.client.request;
@@ -693,25 +877,47 @@ export class Socket<
   /**
    * A reference to the underlying Client transport connection (Engine.IO Socket object).
    *
-   * @public
+   * @example
+   * io.on("connection", (socket) => {
+   *   console.log(socket.conn.transport.name); // prints "polling" or "websocket"
+   *
+   *   socket.conn.once("upgrade", () => {
+   *     console.log(socket.conn.transport.name); // prints "websocket"
+   *   });
+   * });
    */
   public get conn() {
     return this.client.conn;
   }
 
   /**
-   * @public
+   * Returns the rooms the socket is currently in.
+   *
+   * @example
+   * io.on("connection", (socket) => {
+   *   console.log(socket.rooms); // Set { <socket.id> }
+   *
+   *   socket.join("room1");
+   *
+   *   console.log(socket.rooms); // Set { <socket.id>, "room1" }
+   * });
    */
   public get rooms(): Set<Room> {
     return this.adapter.socketRooms(this.id) || new Set();
   }
 
   /**
-   * Adds a listener that will be fired when any event is emitted. The event name is passed as the first argument to the
-   * callback.
+   * Adds a listener that will be fired when any event is received. The event name is passed as the first argument to
+   * the callback.
+   *
+   * @example
+   * io.on("connection", (socket) => {
+   *   socket.onAny((event, ...args) => {
+   *     console.log(`got event ${event}`);
+   *   });
+   * });
    *
    * @param listener
-   * @public
    */
   public onAny(listener: (...args: any[]) => void): this {
     this._anyListeners = this._anyListeners || [];
@@ -720,11 +926,10 @@ export class Socket<
   }
 
   /**
-   * Adds a listener that will be fired when any event is emitted. The event name is passed as the first argument to the
-   * callback. The listener is added to the beginning of the listeners array.
+   * Adds a listener that will be fired when any event is received. The event name is passed as the first argument to
+   * the callback. The listener is added to the beginning of the listeners array.
    *
    * @param listener
-   * @public
    */
   public prependAny(listener: (...args: any[]) => void): this {
     this._anyListeners = this._anyListeners || [];
@@ -733,10 +938,24 @@ export class Socket<
   }
 
   /**
-   * Removes the listener that will be fired when any event is emitted.
+   * Removes the listener that will be fired when any event is received.
+   *
+   * @example
+   * io.on("connection", (socket) => {
+   *   const catchAllListener = (event, ...args) => {
+   *     console.log(`got event ${event}`);
+   *   }
+   *
+   *   socket.onAny(catchAllListener);
+   *
+   *   // remove a specific listener
+   *   socket.offAny(catchAllListener);
+   *
+   *   // or remove all listeners
+   *   socket.offAny();
+   * });
    *
    * @param listener
-   * @public
    */
   public offAny(listener?: (...args: any[]) => void): this {
     if (!this._anyListeners) {
@@ -759,17 +978,117 @@ export class Socket<
   /**
    * Returns an array of listeners that are listening for any event that is specified. This array can be manipulated,
    * e.g. to remove listeners.
-   *
-   * @public
    */
   public listenersAny() {
     return this._anyListeners || [];
   }
 
-  private newBroadcastOperator(): BroadcastOperator<EmitEvents, SocketData> {
+  /**
+   * Adds a listener that will be fired when any event is sent. The event name is passed as the first argument to
+   * the callback.
+   *
+   * Note: acknowledgements sent to the client are not included.
+   *
+   * @example
+   * io.on("connection", (socket) => {
+   *   socket.onAnyOutgoing((event, ...args) => {
+   *     console.log(`sent event ${event}`);
+   *   });
+   * });
+   *
+   * @param listener
+   */
+  public onAnyOutgoing(listener: (...args: any[]) => void): this {
+    this._anyOutgoingListeners = this._anyOutgoingListeners || [];
+    this._anyOutgoingListeners.push(listener);
+    return this;
+  }
+
+  /**
+   * Adds a listener that will be fired when any event is emitted. The event name is passed as the first argument to the
+   * callback. The listener is added to the beginning of the listeners array.
+   *
+   * @example
+   * io.on("connection", (socket) => {
+   *   socket.prependAnyOutgoing((event, ...args) => {
+   *     console.log(`sent event ${event}`);
+   *   });
+   * });
+   *
+   * @param listener
+   */
+  public prependAnyOutgoing(listener: (...args: any[]) => void): this {
+    this._anyOutgoingListeners = this._anyOutgoingListeners || [];
+    this._anyOutgoingListeners.unshift(listener);
+    return this;
+  }
+
+  /**
+   * Removes the listener that will be fired when any event is sent.
+   *
+   * @example
+   * io.on("connection", (socket) => {
+   *   const catchAllListener = (event, ...args) => {
+   *     console.log(`sent event ${event}`);
+   *   }
+   *
+   *   socket.onAnyOutgoing(catchAllListener);
+   *
+   *   // remove a specific listener
+   *   socket.offAnyOutgoing(catchAllListener);
+   *
+   *   // or remove all listeners
+   *   socket.offAnyOutgoing();
+   * });
+   *
+   * @param listener - the catch-all listener
+   */
+  public offAnyOutgoing(listener?: (...args: any[]) => void): this {
+    if (!this._anyOutgoingListeners) {
+      return this;
+    }
+    if (listener) {
+      const listeners = this._anyOutgoingListeners;
+      for (let i = 0; i < listeners.length; i++) {
+        if (listener === listeners[i]) {
+          listeners.splice(i, 1);
+          return this;
+        }
+      }
+    } else {
+      this._anyOutgoingListeners = [];
+    }
+    return this;
+  }
+
+  /**
+   * Returns an array of listeners that are listening for any event that is specified. This array can be manipulated,
+   * e.g. to remove listeners.
+   */
+  public listenersAnyOutgoing() {
+    return this._anyOutgoingListeners || [];
+  }
+
+  /**
+   * Notify the listeners for each packet sent (emit or broadcast)
+   *
+   * @param packet
+   *
+   * @private
+   */
+  private notifyOutgoingListeners(packet: Packet) {
+    if (this._anyOutgoingListeners && this._anyOutgoingListeners.length) {
+      const listeners = this._anyOutgoingListeners.slice();
+      for (const listener of listeners) {
+        listener.apply(this, packet.data);
+      }
+    }
+  }
+
+  private newBroadcastOperator() {
     const flags = Object.assign({}, this.flags);
     this.flags = {};
-    return new BroadcastOperator(
+    return new BroadcastOperator<EmitEvents, SocketData>(
       this.adapter,
       new Set<Room>(),
       new Set<Room>([this.id]),

lib/uws.ts

@@ -25,7 +25,9 @@ export function patchAdapter(app /* : TemplatedApp */) {
     if (isNew) {
       socket.conn.on("upgrade", () => {
         const rooms = this.sids.get(id);
-        subscribe(this.nsp.name, socket, isNew, rooms);
+        if (rooms) {
+          subscribe(this.nsp.name, socket, isNew, rooms);
+        }
       });
     }
   };

package.json

@@ -1,6 +1,6 @@
 {
   "name": "socket.io",
-  "version": "4.4.1",
+  "version": "4.5.3",
   "description": "node.js realtime framework server",
   "keywords": [
     "realtime",
@@ -40,7 +40,7 @@
     "compile": "rimraf ./dist && tsc",
     "test": "npm run format:check && npm run compile && npm run test:types && npm run test:unit",
     "test:types": "tsd",
-    "test:unit": "nyc mocha --require ts-node/register --reporter spec --slow 200 --bail --timeout 10000 test/socket.io.ts",
+    "test:unit": "nyc mocha --require ts-node/register --reporter spec --slow 200 --bail --timeout 10000 test/index.ts",
     "format:check": "prettier --check \"lib/**/*.ts\" \"test/**/*.ts\"",
     "format:fix": "prettier --write \"lib/**/*.ts\" \"test/**/*.ts\"",
     "prepack": "npm run compile"
@@ -49,23 +49,23 @@
     "accepts": "~1.3.4",
     "base64id": "~2.0.0",
     "debug": "~4.3.2",
-    "engine.io": "~6.1.0",
-    "socket.io-adapter": "~2.3.3",
-    "socket.io-parser": "~4.0.4"
+    "engine.io": "~6.2.0",
+    "socket.io-adapter": "~2.4.0",
+    "socket.io-parser": "~4.2.0"
   },
   "devDependencies": {
     "@types/mocha": "^9.0.0",
     "expect.js": "0.3.1",
-    "mocha": "^3.5.3",
+    "mocha": "^10.0.0",
     "nyc": "^15.1.0",
     "prettier": "^2.3.2",
     "rimraf": "^3.0.2",
-    "socket.io-client": "4.4.1",
+    "socket.io-client": "4.5.3",
     "socket.io-client-v2": "npm:socket.io-client@^2.4.0",
-    "superagent": "^6.1.0",
+    "superagent": "^8.0.0",
     "supertest": "^6.1.6",
     "ts-node": "^10.2.1",
-    "tsd": "^0.17.0",
+    "tsd": "^0.21.0",
     "typescript": "^4.4.2",
     "uWebSockets.js": "github:uNetworking/uWebSockets.js#v20.0.0"
   },

test/close.ts

@@ -0,0 +1,181 @@
+import { createServer } from "http";
+import { io as ioc } from "socket.io-client";
+import { join } from "path";
+import { exec } from "child_process";
+import { Server } from "..";
+import expect from "expect.js";
+import { createClient, getPort } from "./support/util";
+import request from "supertest";
+
+// TODO: update superagent as latest release now supports promises
+const eioHandshake = (httpServer): Promise<string> => {
+  return new Promise((resolve) => {
+    request(httpServer)
+      .get("/socket.io/")
+      .query({ transport: "polling", EIO: 4 })
+      .end((err, res) => {
+        const sid = JSON.parse(res.text.substring(1)).sid;
+        resolve(sid);
+      });
+  });
+};
+
+const eioPush = (httpServer, sid: string, body: string): Promise<void> => {
+  return new Promise((resolve) => {
+    request(httpServer)
+      .post("/socket.io/")
+      .send(body)
+      .query({ transport: "polling", EIO: 4, sid })
+      .expect(200)
+      .end(() => {
+        resolve();
+      });
+  });
+};
+
+const eioPoll = (httpServer, sid): Promise<string> => {
+  return new Promise((resolve) => {
+    request(httpServer)
+      .get("/socket.io/")
+      .query({ transport: "polling", EIO: 4, sid })
+      .expect(200)
+      .end((err, res) => {
+        resolve(res.text);
+      });
+  });
+};
+
+describe("close", () => {
+  it("should be able to close sio sending a srv", (done) => {
+    const httpServer = createServer().listen(0);
+    const io = new Server(httpServer);
+    const port = getPort(io);
+    const net = require("net");
+    const server = net.createServer();
+
+    const clientSocket = createClient(io, "/", { reconnection: false });
+
+    clientSocket.on("disconnect", () => {
+      expect(io.sockets.sockets.size).to.equal(0);
+      server.listen(port);
+    });
+
+    clientSocket.on("connect", () => {
+      expect(io.sockets.sockets.size).to.equal(1);
+      io.close();
+    });
+
+    server.once("listening", () => {
+      // PORT should be free
+      server.close((error) => {
+        expect(error).to.be(undefined);
+        done();
+      });
+    });
+  });
+
+  it("should be able to close sio sending a srv", (done) => {
+    const io = new Server(0);
+    const port = getPort(io);
+    const net = require("net");
+    const server = net.createServer();
+
+    const clientSocket = ioc("ws://0.0.0.0:" + port, {
+      reconnection: false,
+    });
+
+    clientSocket.on("disconnect", () => {
+      expect(io.sockets.sockets.size).to.equal(0);
+      server.listen(port);
+    });
+
+    clientSocket.on("connect", () => {
+      expect(io.sockets.sockets.size).to.equal(1);
+      io.close();
+    });
+
+    server.once("listening", () => {
+      // PORT should be free
+      server.close((error) => {
+        expect(error).to.be(undefined);
+        done();
+      });
+    });
+  });
+
+  describe("graceful close", () => {
+    function fixture(filename) {
+      return (
+        '"' +
+        process.execPath +
+        '" "' +
+        join(__dirname, "fixtures", filename) +
+        '"'
+      );
+    }
+
+    it("should stop socket and timers", (done) => {
+      exec(fixture("server-close.ts"), done);
+    });
+  });
+
+  describe("protocol violations", () => {
+    it("should close the connection when receiving several CONNECT packets", async () => {
+      const httpServer = createServer();
+      const io = new Server(httpServer);
+
+      httpServer.listen(0);
+
+      const sid = await eioHandshake(httpServer);
+      // send a first CONNECT packet
+      await eioPush(httpServer, sid, "40");
+      // send another CONNECT packet
+      await eioPush(httpServer, sid, "40");
+      // session is cleanly closed (not discarded, see 'client.close()')
+      // first, we receive the Socket.IO handshake response
+      await eioPoll(httpServer, sid);
+      // then a close packet
+      const body = await eioPoll(httpServer, sid);
+      expect(body).to.be("6\u001e1");
+
+      io.close();
+    });
+
+    it("should close the connection when receiving an EVENT packet while not connected", async () => {
+      const httpServer = createServer();
+      const io = new Server(httpServer);
+
+      httpServer.listen(0);
+
+      const sid = await eioHandshake(httpServer);
+      // send an EVENT packet
+      await eioPush(httpServer, sid, '42["some event"]');
+      // session is cleanly closed, we receive a close packet
+      const body = await eioPoll(httpServer, sid);
+      expect(body).to.be("6\u001e1");
+
+      io.close();
+    });
+
+    it("should close the connection when receiving an invalid packet", async () => {
+      const httpServer = createServer();
+      const io = new Server(httpServer);
+
+      httpServer.listen(0);
+
+      const sid = await eioHandshake(httpServer);
+      // send a CONNECT packet
+      await eioPush(httpServer, sid, "40");
+      // send an invalid packet
+      await eioPush(httpServer, sid, "4abc");
+      // session is cleanly closed (not discarded, see 'client.close()')
+      // first, we receive the Socket.IO handshake response
+      await eioPoll(httpServer, sid);
+      // then a close packet
+      const body = await eioPoll(httpServer, sid);
+      expect(body).to.be("6\u001e1");
+
+      io.close();
+    });
+  });
+});

test/handshake.ts

@@ -0,0 +1,87 @@
+import { Server } from "..";
+import expect from "expect.js";
+import { getPort, success } from "./support/util";
+
+describe("handshake", () => {
+  const request = require("superagent");
+
+  it("should send the Access-Control-Allow-xxx headers on OPTIONS request", (done) => {
+    const io = new Server(0, {
+      cors: {
+        origin: "http://localhost:54023",
+        methods: ["GET", "POST"],
+        allowedHeaders: ["content-type"],
+        credentials: true,
+      },
+    });
+    request
+      .options(`http://localhost:${getPort(io)}/socket.io/default/`)
+      .query({ transport: "polling", EIO: 4 })
+      .set("Origin", "http://localhost:54023")
+      .end((err, res) => {
+        expect(res.status).to.be(204);
+
+        expect(res.headers["access-control-allow-origin"]).to.be(
+          "http://localhost:54023"
+        );
+        expect(res.headers["access-control-allow-methods"]).to.be("GET,POST");
+        expect(res.headers["access-control-allow-headers"]).to.be(
+          "content-type"
+        );
+        expect(res.headers["access-control-allow-credentials"]).to.be("true");
+        success(done, io);
+      });
+  });
+
+  it("should send the Access-Control-Allow-xxx headers on GET request", (done) => {
+    const io = new Server(0, {
+      cors: {
+        origin: "http://localhost:54024",
+        methods: ["GET", "POST"],
+        allowedHeaders: ["content-type"],
+        credentials: true,
+      },
+    });
+    request
+      .get(`http://localhost:${getPort(io)}/socket.io/default/`)
+      .query({ transport: "polling", EIO: 4 })
+      .set("Origin", "http://localhost:54024")
+      .end((err, res) => {
+        expect(res.status).to.be(200);
+
+        expect(res.headers["access-control-allow-origin"]).to.be(
+          "http://localhost:54024"
+        );
+        expect(res.headers["access-control-allow-credentials"]).to.be("true");
+        success(done, io);
+      });
+  });
+
+  it("should allow request if custom function in opts.allowRequest returns true", (done) => {
+    const io = new Server(0, {
+      allowRequest: (req, callback) => callback(null, true),
+    });
+
+    request
+      .get(`http://localhost:${getPort(io)}/socket.io/default/`)
+      .query({ transport: "polling", EIO: 4 })
+      .end((err, res) => {
+        expect(res.status).to.be(200);
+        success(done, io);
+      });
+  });
+
+  it("should disallow request if custom function in opts.allowRequest returns false", (done) => {
+    const io = new Server(0, {
+      allowRequest: (req, callback) => callback(null, false),
+    });
+    request
+      .get(`http://localhost:${getPort(io)}/socket.io/default/`)
+      .set("origin", "http://foo.example")
+      .query({ transport: "polling", EIO: 4 })
+      .end((err, res) => {
+        expect(res.status).to.be(403);
+        success(done, io);
+      });
+  });
+});

test/index.ts

@@ -0,0 +1,23 @@
+"use strict";
+
+import expect from "expect.js";
+
+describe("socket.io", () => {
+  it("should be the same version as client", () => {
+    const version = require("../package").version;
+    expect(version).to.be(require("socket.io-client/package.json").version);
+  });
+
+  require("./server-attachment");
+  require("./handshake");
+  require("./close");
+  require("./namespaces");
+  require("./socket");
+  require("./messaging-many");
+  require("./middleware");
+  require("./socket-middleware");
+  require("./v2-compatibility");
+  require("./socket-timeout");
+  require("./uws");
+  require("./utility-methods");
+});

test/messaging-many.ts

@@ -0,0 +1,501 @@
+import { Server } from "..";
+import expect from "expect.js";
+import {
+  createClient,
+  createPartialDone,
+  success,
+  successFn,
+  waitFor,
+} from "./support/util";
+
+describe("messaging many", () => {
+  it("emits to a namespace", (done) => {
+    const io = new Server(0);
+    const socket1 = createClient(io, "/", { multiplex: false });
+    const socket2 = createClient(io, "/", { multiplex: false });
+    const socket3 = createClient(io, "/test");
+
+    const partialDone = createPartialDone(
+      2,
+      successFn(done, io, socket1, socket2, socket3)
+    );
+
+    socket1.on("a", (a) => {
+      expect(a).to.be("b");
+      partialDone();
+    });
+    socket2.on("a", (a) => {
+      expect(a).to.be("b");
+      partialDone();
+    });
+    socket3.on("a", () => {
+      done(new Error("not"));
+    });
+
+    let sockets = 3;
+    io.on("connection", () => {
+      --sockets || emit();
+    });
+    io.of("/test", () => {
+      --sockets || emit();
+    });
+
+    function emit() {
+      io.emit("a", "b");
+    }
+  });
+
+  it("emits binary data to a namespace", (done) => {
+    const io = new Server(0);
+    const socket1 = createClient(io, "/", { multiplex: false });
+    const socket2 = createClient(io, "/", { multiplex: false });
+    const socket3 = createClient(io, "/test");
+
+    const partialDone = createPartialDone(
+      2,
+      successFn(done, io, socket1, socket2, socket3)
+    );
+
+    socket1.on("bin", (a) => {
+      expect(Buffer.isBuffer(a)).to.be(true);
+      partialDone();
+    });
+    socket2.on("bin", (a) => {
+      expect(Buffer.isBuffer(a)).to.be(true);
+      partialDone();
+    });
+    socket3.on("bin", () => {
+      done(new Error("not"));
+    });
+
+    let sockets = 3;
+    io.on("connection", () => {
+      --sockets || emit();
+    });
+    io.of("/test", () => {
+      --sockets || emit();
+    });
+
+    function emit() {
+      io.emit("bin", Buffer.alloc(10));
+    }
+  });
+
+  it("emits to the rest", (done) => {
+    const io = new Server(0);
+    const socket1 = createClient(io, "/", { multiplex: false });
+    const socket2 = createClient(io, "/", { multiplex: false });
+    const socket3 = createClient(io, "/test");
+
+    socket1.on("a", (a) => {
+      expect(a).to.be("b");
+      socket1.emit("finish");
+    });
+    socket2.emit("broadcast");
+    socket2.on("a", () => {
+      done(new Error("done"));
+    });
+    socket3.on("a", () => {
+      done(new Error("not"));
+    });
+
+    io.on("connection", (socket) => {
+      socket.on("broadcast", () => {
+        socket.broadcast.emit("a", "b");
+      });
+      socket.on("finish", () => {
+        success(done, io, socket1, socket2, socket3);
+      });
+    });
+  });
+
+  it("emits to rooms", (done) => {
+    const io = new Server(0);
+    const socket1 = createClient(io, "/", { multiplex: false });
+    const socket2 = createClient(io, "/", { multiplex: false });
+
+    socket2.on("a", () => {
+      done(new Error("not"));
+    });
+    socket1.on("a", () => {
+      success(done, io, socket1, socket2);
+    });
+    socket1.emit("join", "woot");
+    socket1.emit("emit", "woot");
+
+    io.on("connection", (socket) => {
+      socket.on("join", (room, fn) => {
+        socket.join(room);
+        fn && fn();
+      });
+
+      socket.on("emit", (room) => {
+        io.in(room).emit("a");
+      });
+    });
+  });
+
+  it("emits to rooms avoiding dupes", (done) => {
+    const io = new Server(0);
+    const socket1 = createClient(io, "/", { multiplex: false });
+    const socket2 = createClient(io, "/", { multiplex: false });
+
+    const partialDone = createPartialDone(
+      2,
+      successFn(done, io, socket1, socket2)
+    );
+
+    socket2.on("a", () => {
+      done(new Error("not"));
+    });
+    socket1.on("a", partialDone);
+    socket2.on("b", partialDone);
+
+    socket1.emit("join", "woot");
+    socket1.emit("join", "test");
+    socket2.emit("join", "third", () => {
+      socket2.emit("emit");
+    });
+
+    io.on("connection", (socket) => {
+      socket.on("join", (room, fn) => {
+        socket.join(room);
+        fn && fn();
+      });
+
+      socket.on("emit", () => {
+        io.in("woot").in("test").emit("a");
+        io.in("third").emit("b");
+      });
+    });
+  });
+
+  it("broadcasts to rooms", (done) => {
+    const io = new Server(0);
+    const socket1 = createClient(io, "/", { multiplex: false });
+    const socket2 = createClient(io, "/", { multiplex: false });
+    const socket3 = createClient(io, "/", { multiplex: false });
+
+    const partialDone = createPartialDone(
+      2,
+      successFn(done, io, socket1, socket2, socket3)
+    );
+
+    socket1.emit("join", "woot");
+    socket2.emit("join", "test");
+    socket3.emit("join", "test", () => {
+      socket3.emit("broadcast");
+    });
+
+    socket1.on("a", () => {
+      done(new Error("not"));
+    });
+    socket2.on("a", () => {
+      partialDone();
+    });
+    socket3.on("a", () => {
+      done(new Error("not"));
+    });
+    socket3.on("b", () => {
+      partialDone();
+    });
+
+    io.on("connection", (socket) => {
+      socket.on("join", (room, fn) => {
+        socket.join(room);
+        fn && fn();
+      });
+
+      socket.on("broadcast", () => {
+        socket.broadcast.to("test").emit("a");
+        socket.emit("b");
+      });
+    });
+  });
+
+  it("broadcasts binary data to rooms", (done) => {
+    const io = new Server(0);
+    const socket1 = createClient(io, "/", { multiplex: false });
+    const socket2 = createClient(io, "/", { multiplex: false });
+    const socket3 = createClient(io, "/", { multiplex: false });
+
+    const partialDone = createPartialDone(
+      2,
+      successFn(done, io, socket1, socket2, socket3)
+    );
+
+    socket1.emit("join", "woot");
+    socket2.emit("join", "test");
+    socket3.emit("join", "test", () => {
+      socket3.emit("broadcast");
+    });
+
+    socket1.on("bin", (data) => {
+      throw new Error("got bin in socket1");
+    });
+    socket2.on("bin", (data) => {
+      expect(Buffer.isBuffer(data)).to.be(true);
+      partialDone();
+    });
+    socket2.on("bin2", (data) => {
+      throw new Error("socket2 got bin2");
+    });
+    socket3.on("bin", (data) => {
+      throw new Error("socket3 got bin");
+    });
+    socket3.on("bin2", (data) => {
+      expect(Buffer.isBuffer(data)).to.be(true);
+      partialDone();
+    });
+
+    io.on("connection", (socket) => {
+      socket.on("join", (room, fn) => {
+        socket.join(room);
+        fn && fn();
+      });
+      socket.on("broadcast", () => {
+        socket.broadcast.to("test").emit("bin", Buffer.alloc(5));
+        socket.emit("bin2", Buffer.alloc(5));
+      });
+    });
+  });
+
+  it("keeps track of rooms", (done) => {
+    const io = new Server(0);
+    const socket = createClient(io);
+
+    io.on("connection", (s) => {
+      s.join("a");
+      expect(s.rooms).to.contain(s.id, "a");
+      s.join("b");
+      expect(s.rooms).to.contain(s.id, "a", "b");
+      s.join("c");
+      expect(s.rooms).to.contain(s.id, "a", "b", "c");
+      s.leave("b");
+      expect(s.rooms).to.contain(s.id, "a", "c");
+      (s as any).leaveAll();
+      expect(s.rooms.size).to.eql(0);
+
+      success(done, io, socket);
+    });
+  });
+
+  it("deletes empty rooms", (done) => {
+    const io = new Server(0);
+    const socket = createClient(io);
+
+    io.on("connection", (s) => {
+      s.join("a");
+      expect(s.nsp.adapter.rooms).to.contain("a");
+      s.leave("a");
+      expect(s.nsp.adapter.rooms).to.not.contain("a");
+
+      success(done, io, socket);
+    });
+  });
+
+  it("should properly cleanup left rooms", (done) => {
+    const io = new Server(0);
+    const socket = createClient(io);
+
+    io.on("connection", (s) => {
+      s.join("a");
+      expect(s.rooms).to.contain(s.id, "a");
+      s.join("b");
+      expect(s.rooms).to.contain(s.id, "a", "b");
+      s.leave("unknown");
+      expect(s.rooms).to.contain(s.id, "a", "b");
+      (s as any).leaveAll();
+      expect(s.rooms.size).to.eql(0);
+
+      success(done, io, socket);
+    });
+  });
+
+  it("allows to join several rooms at once", (done) => {
+    const io = new Server(0);
+    const socket = createClient(io);
+
+    io.on("connection", (s) => {
+      s.join(["a", "b", "c"]);
+      expect(s.rooms).to.contain(s.id, "a", "b", "c");
+      success(done, io, socket);
+    });
+  });
+
+  it("should exclude specific sockets when broadcasting", (done) => {
+    const io = new Server(0);
+    const socket1 = createClient(io, "/", { multiplex: false });
+    const socket2 = createClient(io, "/", { multiplex: false });
+    const socket3 = createClient(io, "/", { multiplex: false });
+
+    socket2.on("a", () => {
+      done(new Error("not"));
+    });
+    socket3.on("a", () => {
+      done(new Error("not"));
+    });
+    socket1.on("a", successFn(done, io, socket1, socket2, socket3));
+
+    io.on("connection", (socket) => {
+      socket.on("exclude", (id) => {
+        socket.broadcast.except(id).emit("a");
+      });
+    });
+
+    socket2.on("connect", () => {
+      socket3.emit("exclude", socket2.id);
+    });
+  });
+
+  it("should exclude a specific room when broadcasting", (done) => {
+    const io = new Server(0);
+    const socket1 = createClient(io, "/", { multiplex: false });
+    const socket2 = createClient(io, "/", { multiplex: false });
+    const socket3 = createClient(io, "/", { multiplex: false });
+
+    socket2.on("a", () => {
+      done(new Error("not"));
+    });
+    socket3.on("a", () => {
+      done(new Error("not"));
+    });
+    socket1.on("a", successFn(done, io, socket1, socket2, socket3));
+
+    io.on("connection", (socket) => {
+      socket.on("join", (room, cb) => {
+        socket.join(room);
+        cb();
+      });
+      socket.on("broadcast", () => {
+        socket.broadcast.except("room1").emit("a");
+      });
+    });
+
+    socket2.emit("join", "room1", () => {
+      socket3.emit("broadcast");
+    });
+  });
+
+  it("should return an immutable broadcast operator", (done) => {
+    const io = new Server(0);
+    const clientSocket = createClient(io);
+
+    io.on("connection", (socket) => {
+      const operator = socket.local
+        .compress(false)
+        .to(["room1", "room2"])
+        .except("room3");
+      operator.compress(true).emit("hello");
+      operator.volatile.emit("hello");
+      operator.to("room4").emit("hello");
+      operator.except("room5").emit("hello");
+      socket.emit("hello");
+      socket.to("room6").emit("hello");
+      // @ts-ignore
+      expect(operator.rooms).to.contain("room1", "room2");
+      // @ts-ignore
+      expect(operator.rooms).to.not.contain("room4", "room5", "room6");
+      // @ts-ignore
+      expect(operator.exceptRooms).to.contain("room3");
+      // @ts-ignore
+      expect(operator.flags).to.eql({ local: true, compress: false });
+
+      success(done, io, clientSocket);
+    });
+  });
+
+  it("should broadcast and expect multiple acknowledgements", (done) => {
+    const io = new Server(0);
+    const socket1 = createClient(io, "/", { multiplex: false });
+    const socket2 = createClient(io, "/", { multiplex: false });
+    const socket3 = createClient(io, "/", { multiplex: false });
+
+    socket1.on("some event", (cb) => {
+      cb(1);
+    });
+
+    socket2.on("some event", (cb) => {
+      cb(2);
+    });
+
+    socket3.on("some event", (cb) => {
+      cb(3);
+    });
+
+    Promise.all([
+      waitFor(socket1, "connect"),
+      waitFor(socket2, "connect"),
+      waitFor(socket3, "connect"),
+    ]).then(() => {
+      io.timeout(2000).emit("some event", (err, responses) => {
+        expect(err).to.be(null);
+        expect(responses).to.have.length(3);
+        expect(responses).to.contain(1, 2, 3);
+
+        success(done, io, socket1, socket2, socket3);
+      });
+    });
+  });
+
+  it("should fail when a client does not acknowledge the event in the given delay", (done) => {
+    const io = new Server(0);
+    const socket1 = createClient(io, "/", { multiplex: false });
+    const socket2 = createClient(io, "/", { multiplex: false });
+    const socket3 = createClient(io, "/", { multiplex: false });
+
+    socket1.on("some event", (cb) => {
+      cb(1);
+    });
+
+    socket2.on("some event", (cb) => {
+      cb(2);
+    });
+
+    socket3.on("some event", () => {
+      // timeout
+    });
+
+    Promise.all([
+      waitFor(socket1, "connect"),
+      waitFor(socket2, "connect"),
+      waitFor(socket3, "connect"),
+    ]).then(() => {
+      io.timeout(200).emit("some event", (err, responses) => {
+        expect(err).to.be.an(Error);
+        expect(responses).to.have.length(2);
+        expect(responses).to.contain(1, 2);
+
+        success(done, io, socket1, socket2, socket3);
+      });
+    });
+  });
+
+  it("should broadcast and return if the packet is sent to 0 client", (done) => {
+    const io = new Server(0);
+    const socket1 = createClient(io, "/", { multiplex: false });
+    const socket2 = createClient(io, "/", { multiplex: false });
+    const socket3 = createClient(io, "/", { multiplex: false });
+
+    socket1.on("some event", () => {
+      done(new Error("should not happen"));
+    });
+
+    socket2.on("some event", () => {
+      done(new Error("should not happen"));
+    });
+
+    socket3.on("some event", () => {
+      done(new Error("should not happen"));
+    });
+
+    io.to("room123")
+      .timeout(200)
+      .emit("some event", (err, responses) => {
+        expect(err).to.be(null);
+        expect(responses).to.have.length(0);
+
+        success(done, io, socket1, socket2, socket3);
+      });
+  });
+});

test/middleware.ts

@@ -0,0 +1,210 @@
+import { Server, Socket } from "..";
+import expect from "expect.js";
+import {
+  success,
+  createClient,
+  successFn,
+  createPartialDone,
+} from "./support/util";
+
+describe("middleware", () => {
+  it("should call functions", (done) => {
+    const io = new Server(0);
+
+    let run = 0;
+    io.use((socket, next) => {
+      expect(socket).to.be.a(Socket);
+      run++;
+      next();
+    });
+    io.use((socket, next) => {
+      expect(socket).to.be.a(Socket);
+      run++;
+      next();
+    });
+
+    const socket = createClient(io);
+    socket.on("connect", () => {
+      expect(run).to.be(2);
+
+      success(done, io, socket);
+    });
+  });
+
+  it("should pass errors", (done) => {
+    const io = new Server(0);
+
+    io.use((socket, next) => {
+      next(new Error("Authentication error"));
+    });
+    io.use((socket, next) => {
+      done(new Error("nope"));
+    });
+
+    const socket = createClient(io);
+    socket.on("connect", () => {
+      done(new Error("nope"));
+    });
+    socket.on("connect_error", (err) => {
+      expect(err.message).to.be("Authentication error");
+
+      success(done, io, socket);
+    });
+  });
+
+  it("should pass an object", (done) => {
+    const io = new Server(0);
+
+    io.use((socket, next) => {
+      const err = new Error("Authentication error");
+      // @ts-ignore
+      err.data = { a: "b", c: 3 };
+      next(err);
+    });
+
+    const socket = createClient(io);
+    socket.on("connect", () => {
+      done(new Error("nope"));
+    });
+    socket.on("connect_error", (err) => {
+      expect(err).to.be.an(Error);
+      expect(err.message).to.eql("Authentication error");
+      // @ts-ignore
+      expect(err.data).to.eql({ a: "b", c: 3 });
+
+      success(done, io, socket);
+    });
+  });
+
+  it("should only call connection after fns", (done) => {
+    const io = new Server(0);
+
+    io.use((socket: any, next) => {
+      socket.name = "guillermo";
+      next();
+    });
+
+    const clientSocket = createClient(io);
+    io.on("connection", (socket) => {
+      expect((socket as any).name).to.be("guillermo");
+
+      success(done, io, clientSocket);
+    });
+  });
+
+  it("should only call connection after (lengthy) fns", (done) => {
+    const io = new Server(0);
+
+    let authenticated = false;
+
+    io.use((socket, next) => {
+      setTimeout(() => {
+        authenticated = true;
+        next();
+      }, 300);
+    });
+
+    const socket = createClient(io);
+    socket.on("connect", () => {
+      expect(authenticated).to.be(true);
+
+      success(done, io, socket);
+    });
+  });
+
+  it("should be ignored if socket gets closed", (done) => {
+    const io = new Server(0);
+
+    let socket;
+    io.use((s, next) => {
+      socket.io.engine.close();
+      s.client.conn.on("close", () => {
+        process.nextTick(next);
+        setTimeout(() => {
+          success(done, io, socket);
+        }, 50);
+      });
+    });
+
+    socket = createClient(io);
+    io.on("connection", (socket) => {
+      done(new Error("should not fire"));
+    });
+  });
+
+  it("should call functions in expected order", (done) => {
+    const io = new Server(0);
+
+    const result: number[] = [];
+
+    io.use(() => {
+      done(new Error("should not fire"));
+    });
+    io.of("/chat").use((socket, next) => {
+      result.push(1);
+      setTimeout(next, 50);
+    });
+    io.of("/chat").use((socket, next) => {
+      result.push(2);
+      setTimeout(next, 50);
+    });
+    io.of("/chat").use((socket, next) => {
+      result.push(3);
+      setTimeout(next, 50);
+    });
+
+    const chat = createClient(io, "/chat");
+    chat.on("connect", () => {
+      expect(result).to.eql([1, 2, 3]);
+
+      success(done, io, chat);
+    });
+  });
+
+  it("should disable the merge of handshake packets", (done) => {
+    const io = new Server(0);
+
+    io.use((socket, next) => {
+      next();
+    });
+
+    const socket = createClient(io);
+    socket.on("connect", successFn(done, io, socket));
+  });
+
+  it("should work with a custom namespace", (done) => {
+    const io = new Server(0);
+    const socket1 = createClient(io, "/");
+    const socket2 = createClient(io, "/chat");
+
+    const partialDone = createPartialDone(
+      2,
+      successFn(done, io, socket1, socket2)
+    );
+
+    io.of("/chat").use((socket, next) => {
+      next();
+    });
+
+    socket1.on("connect", partialDone);
+    socket2.on("connect", partialDone);
+  });
+
+  it("should only set `connected` to true after the middleware execution", (done) => {
+    const io = new Server(0);
+    const clientSocket = createClient(io, "/");
+
+    io.use((socket, next) => {
+      expect(socket.connected).to.be(false);
+      expect(socket.disconnected).to.be(true);
+      next();
+    });
+
+    io.on("connection", (socket) => {
+      expect(socket.connected).to.be(true);
+      expect(socket.disconnected).to.be(false);
+
+      success(done, io, clientSocket);
+    });
+  });
+});

test/namespaces.ts

@@ -0,0 +1,575 @@
+import type { SocketId } from "socket.io-adapter";
+import { Server, Namespace, Socket } from "..";
+import expect from "expect.js";
+import {
+  success,
+  createClient,
+  successFn,
+  createPartialDone,
+} from "./support/util";
+
+describe("namespaces", () => {
+  it("should be accessible through .sockets", () => {
+    const io = new Server();
+    expect(io.sockets).to.be.a(Namespace);
+  });
+
+  it("should be aliased", () => {
+    const io = new Server();
+    expect(io.use).to.be.a("function");
+    expect(io.to).to.be.a("function");
+    expect(io["in"]).to.be.a("function");
+    expect(io.emit).to.be.a("function");
+    expect(io.send).to.be.a("function");
+    expect(io.write).to.be.a("function");
+    expect(io.allSockets).to.be.a("function");
+    expect(io.compress).to.be.a("function");
+  });
+
+  it("should return an immutable broadcast operator", () => {
+    const io = new Server();
+    const operator = io.local.to(["room1", "room2"]).except("room3");
+    operator.compress(true).emit("hello");
+    operator.volatile.emit("hello");
+    operator.to("room4").emit("hello");
+    operator.except("room5").emit("hello");
+    io.to("room6").emit("hello");
+    // @ts-ignore
+    expect(operator.rooms).to.contain("room1", "room2");
+    // @ts-ignore
+    expect(operator.exceptRooms).to.contain("room3");
+    // @ts-ignore
+    expect(operator.flags).to.eql({ local: true });
+  });
+
+  it("should automatically connect", (done) => {
+    const io = new Server(0);
+    const socket = createClient(io);
+    socket.on("connect", successFn(done, io, socket));
+  });
+
+  it("should fire a `connection` event", (done) => {
+    const io = new Server(0);
+    const clientSocket = createClient(io);
+
+    io.on("connection", (socket) => {
+      expect(socket).to.be.a(Socket);
+      success(done, io, clientSocket);
+    });
+  });
+
+  it("should fire a `connect` event", (done) => {
+    const io = new Server(0);
+    const clientSocket = createClient(io);
+
+    io.on("connect", (socket) => {
+      expect(socket).to.be.a(Socket);
+      success(done, io, clientSocket);
+    });
+  });
+
+  it("should work with many sockets", (done) => {
+    const io = new Server(0);
+    io.of("/chat");
+    io.of("/news");
+    const chat = createClient(io, "/chat");
+    const news = createClient(io, "/news");
+
+    let total = 2;
+    chat.on("connect", () => {
+      --total || success(done, io, chat, news);
+    });
+    news.on("connect", () => {
+      --total || success(done, io, chat, news);
+    });
+  });
+
+  it('should be able to equivalently start with "" or "/" on server', (done) => {
+    const io = new Server(0);
+    const c1 = createClient(io, "/");
+    const c2 = createClient(io, "/abc");
+
+    let total = 2;
+    io.of("").on("connection", () => {
+      --total || success(done, io, c1, c2);
+    });
+    io.of("abc").on("connection", () => {
+      --total || success(done, io, c1, c2);
+    });
+  });
+
+  it('should be equivalent for "" and "/" on client', (done) => {
+    const io = new Server(0);
+    const c1 = createClient(io, "");
+
+    io.of("/").on("connection", successFn(done, io, c1));
+  });
+
+  it("should work with `of` and many sockets", (done) => {
+    const io = new Server(0);
+    const chat = createClient(io, "/chat");
+    const news = createClient(io, "/news");
+
+    let total = 2;
+    io.of("/news").on("connection", (socket) => {
+      expect(socket).to.be.a(Socket);
+      --total || success(done, io, chat, news);
+    });
+    io.of("/news").on("connection", (socket) => {
+      expect(socket).to.be.a(Socket);
+      --total || success(done, io, chat, news);
+    });
+  });
+
+  it("should work with `of` second param", (done) => {
+    const io = new Server(0);
+    const chat = createClient(io, "/chat");
+    const news = createClient(io, "/news");
+
+    let total = 2;
+    io.of("/news", (socket) => {
+      expect(socket).to.be.a(Socket);
+      --total || success(done, io, chat, news);
+    });
+    io.of("/news", (socket) => {
+      expect(socket).to.be.a(Socket);
+      --total || success(done, io, chat, news);
+    });
+  });
+
+  it("should disconnect upon transport disconnection", (done) => {
+    const io = new Server(0);
+    const chat = createClient(io, "/chat");
+    const news = createClient(io, "/news");
+
+    let total = 2;
+    let totald = 2;
+    let s;
+    io.of("/news", (socket) => {
+      socket.on("disconnect", (reason) => {
+        --totald || success(done, io, chat, news);
+      });
+      --total || close();
+    });
+    io.of("/chat", (socket) => {
+      s = socket;
+      socket.on("disconnect", (reason) => {
+        --totald || success(done, io, chat, news);
+      });
+      --total || close();
+    });
+    function close() {
+      s.disconnect(true);
+    }
+  });
+
+  it("should fire a `disconnecting` event just before leaving all rooms", (done) => {
+    const io = new Server(0);
+    const socket = createClient(io);
+
+    io.on("connection", (s) => {
+      s.join("a");
+      // FIXME not sure why process.nextTick() is needed here
+      process.nextTick(() => s.disconnect());
+
+      let total = 2;
+      s.on("disconnecting", (reason) => {
+        expect(s.rooms).to.contain(s.id, "a");
+        total--;
+      });
+
+      s.on("disconnect", (reason) => {
+        expect(s.rooms.size).to.eql(0);
+        --total || success(done, io, socket);
+      });
+    });
+  });
+
+  it("should return error connecting to non-existent namespace", (done) => {
+    const io = new Server(0);
+    const socket = createClient(io, "/doesnotexist");
+
+    socket.on("connect_error", (err) => {
+      expect(err.message).to.be("Invalid namespace");
+      success(done, io);
+    });
+  });
+
+  it("should not reuse same-namespace connections", (done) => {
+    const io = new Server(0);
+    const clientSocket1 = createClient(io);
+    const clientSocket2 = createClient(io);
+
+    let connections = 0;
+    io.on("connection", () => {
+      connections++;
+      if (connections === 2) {
+        success(done, io, clientSocket1, clientSocket2);
+      }
+    });
+  });
+
+  it("should find all clients in a namespace", (done) => {
+    const io = new Server(0);
+    const chatSids: string[] = [];
+    let otherSid: SocketId | null = null;
+
+    const c1 = createClient(io, "/chat");
+    const c2 = createClient(io, "/chat", { forceNew: true });
+    const c3 = createClient(io, "/other", { forceNew: true });
+
+    let total = 3;
+    io.of("/chat").on("connection", (socket) => {
+      chatSids.push(socket.id);
+      --total || getSockets();
+    });
+    io.of("/other").on("connection", (socket) => {
+      otherSid = socket.id;
+      --total || getSockets();
+    });
+
+    async function getSockets() {
+      const sids = await io.of("/chat").allSockets();
+
+      expect(sids).to.contain(chatSids[0], chatSids[1]);
+      expect(sids).to.not.contain(otherSid);
+      success(done, io, c1, c2, c3);
+    }
+  });
+
+  it("should find all clients in a namespace room", (done) => {
+    const io = new Server(0);
+    let chatFooSid: SocketId | null = null;
+    let chatBarSid: SocketId | null = null;
+    let otherSid: SocketId | null = null;
+
+    const c1 = createClient(io, "/chat");
+    const c2 = createClient(io, "/chat", { forceNew: true });
+    const c3 = createClient(io, "/other", { forceNew: true });
+
+    let chatIndex = 0;
+    let total = 3;
+    io.of("/chat").on("connection", (socket) => {
+      if (chatIndex++) {
+        socket.join("foo");
+        chatFooSid = socket.id;
+        --total || getSockets();
+      } else {
+        socket.join("bar");
+        chatBarSid = socket.id;
+        --total || getSockets();
+      }
+    });
+    io.of("/other").on("connection", (socket) => {
+      socket.join("foo");
+      otherSid = socket.id;
+      --total || getSockets();
+    });
+
+    async function getSockets() {
+      const sids = await io.of("/chat").in("foo").allSockets();
+
+      expect(sids).to.contain(chatFooSid);
+      expect(sids).to.not.contain(chatBarSid);
+      expect(sids).to.not.contain(otherSid);
+      success(done, io, c1, c2, c3);
+    }
+  });
+
+  it("should find all clients across namespace rooms", (done) => {
+    const io = new Server(0);
+    let chatFooSid: SocketId | null = null;
+    let chatBarSid: SocketId | null = null;
+    let otherSid: SocketId | null = null;
+
+    const c1 = createClient(io, "/chat");
+    const c2 = createClient(io, "/chat", { forceNew: true });
+    const c3 = createClient(io, "/other", { forceNew: true });
+
+    let chatIndex = 0;
+    let total = 3;
+    io.of("/chat").on("connection", (socket) => {
+      if (chatIndex++) {
+        socket.join("foo");
+        chatFooSid = socket.id;
+        --total || getSockets();
+      } else {
+        socket.join("bar");
+        chatBarSid = socket.id;
+        --total || getSockets();
+      }
+    });
+    io.of("/other").on("connection", (socket) => {
+      socket.join("foo");
+      otherSid = socket.id;
+      --total || getSockets();
+    });
+
+    async function getSockets() {
+      const sids = await io.of("/chat").allSockets();
+      expect(sids).to.contain(chatFooSid, chatBarSid);
+      expect(sids).to.not.contain(otherSid);
+      success(done, io, c1, c2, c3);
+    }
+  });
+
+  it("should not emit volatile event after regular event", (done) => {
+    const io = new Server(0);
+
+    let counter = 0;
+    io.of("/chat").on("connection", (s) => {
+      // Wait to make sure there are no packets being sent for opening the connection
+      setTimeout(() => {
+        io.of("/chat").emit("ev", "data");
+        io.of("/chat").volatile.emit("ev", "data");
+      }, 50);
+    });
+
+    const socket = createClient(io, "/chat");
+    socket.on("ev", () => {
+      counter++;
+    });
+
+    setTimeout(() => {
+      expect(counter).to.be(1);
+      success(done, io, socket);
+    }, 500);
+  });
+
+  it("should emit volatile event", (done) => {
+    const io = new Server(0);
+
+    let counter = 0;
+    io.of("/chat").on("connection", (s) => {
+      // Wait to make sure there are no packets being sent for opening the connection
+      setTimeout(() => {
+        io.of("/chat").volatile.emit("ev", "data");
+      }, 100);
+    });
+
+    const socket = createClient(io, "/chat");
+    socket.on("ev", () => {
+      counter++;
+    });
+
+    setTimeout(() => {
+      expect(counter).to.be(1);
+      success(done, io, socket);
+    }, 500);
+  });
+
+  it("should enable compression by default", (done) => {
+    const io = new Server(0);
+    const socket = createClient(io, "/chat");
+
+    io.of("/chat").on("connection", (s) => {
+      s.conn.once("packetCreate", (packet) => {
+        expect(packet.options.compress).to.be(true);
+        success(done, io, socket);
+      });
+      io.of("/chat").emit("woot", "hi");
+    });
+  });
+
+  it("should disable compression", (done) => {
+    const io = new Server(0);
+    const socket = createClient(io, "/chat");
+
+    io.of("/chat").on("connection", (s) => {
+      s.conn.once("packetCreate", (packet) => {
+        expect(packet.options.compress).to.be(false);
+        success(done, io, socket);
+      });
+      io.of("/chat").compress(false).emit("woot", "hi");
+    });
+  });
+
+  it("should throw on reserved event", () => {
+    const io = new Server();
+
+    expect(() => io.emit("connect")).to.throwException(
+      /"connect" is a reserved event name/
+    );
+  });
+
+  it("should close a client without namespace", (done) => {
+    const io = new Server(0, {
+      connectTimeout: 10,
+    });
+
+    const socket = createClient(io);
+
+    // @ts-ignore
+    socket.io.engine.write = () => {}; // prevent the client from sending a CONNECT packet
+
+    socket.on("disconnect", successFn(done, io, socket));
+  });
+
+  it("should exclude a specific socket when emitting", (done) => {
+    const io = new Server(0);
+
+    const socket1 = createClient(io, "/");
+    const socket2 = createClient(io, "/");
+
+    socket2.on("a", () => {
+      done(new Error("should not happen"));
+    });
+    socket1.on("a", successFn(done, io, socket1, socket2));
+
+    socket2.on("connect", () => {
+      io.except(socket2.id).emit("a");
+    });
+  });
+
+  it("should exclude a specific socket when emitting (in a namespace)", (done) => {
+    const io = new Server(0);
+
+    const nsp = io.of("/nsp");
+
+    const socket1 = createClient(io, "/nsp");
+    const socket2 = createClient(io, "/nsp");
+
+    socket2.on("a", () => {
+      done(new Error("not"));
+    });
+    socket1.on("a", successFn(done, io, socket1, socket2));
+
+    socket2.on("connect", () => {
+      nsp.except(socket2.id).emit("a");
+    });
+  });
+
+  it("should exclude a specific room when emitting", (done) => {
+    const io = new Server(0);
+
+    const nsp = io.of("/nsp");
+
+    const socket1 = createClient(io, "/nsp");
+    const socket2 = createClient(io, "/nsp");
+
+    socket1.on("a", successFn(done, io, socket1, socket2));
+    socket2.on("a", () => {
+      done(new Error("not"));
+    });
+
+    nsp.on("connection", (socket) => {
+      socket.on("broadcast", () => {
+        socket.join("room1");
+        nsp.except("room1").emit("a");
+      });
+    });
+
+    socket2.emit("broadcast");
+  });
+
+  it("should emit an 'new_namespace' event", (done) => {
+    const io = new Server();
+
+    io.on("new_namespace", (namespace) => {
+      expect(namespace.name).to.eql("/nsp");
+      done();
+    });
+
+    io.of("/nsp");
+  });
+
+  describe("dynamic namespaces", () => {
+    it("should allow connections to dynamic namespaces with a regex", (done) => {
+      const io = new Server(0);
+      const socket = createClient(io, "/dynamic-101");
+      const partialDone = createPartialDone(4, successFn(done, io, socket));
+
+      let dynamicNsp = io
+        .of(/^\/dynamic-\d+$/)
+        .on("connect", (socket) => {
+          expect(socket.nsp.name).to.be("/dynamic-101");
+          dynamicNsp.emit("hello", 1, "2", { 3: "4" });
+          partialDone();
+        })
+        .use((socket, next) => {
+          next();
+          partialDone();
+        });
+      socket.on("connect_error", (err) => {
+        expect().fail();
+      });
+      socket.on("connect", () => {
+        partialDone();
+      });
+      socket.on("hello", (a, b, c) => {
+        expect(a).to.eql(1);
+        expect(b).to.eql("2");
+        expect(c).to.eql({ 3: "4" });
+        partialDone();
+      });
+    });
+
+    it("should allow connections to dynamic namespaces with a function", (done) => {
+      const io = new Server(0);
+      const socket = createClient(io, "/dynamic-101");
+
+      io.of((name, query, next) => next(null, "/dynamic-101" === name));
+      socket.on("connect", successFn(done, io, socket));
+    });
+
+    it("should disallow connections when no dynamic namespace matches", (done) => {
+      const io = new Server(0);
+      const socket = createClient(io, "/abc");
+      io.of(/^\/dynamic-\d+$/);
+      io.of((name, query, next) => next(null, "/dynamic-101" === name));
+
+      socket.on("connect_error", (err) => {
+        expect(err.message).to.be("Invalid namespace");
+        success(done, io, socket);
+      });
+    });
+
+    it("should emit an 'new_namespace' event for a dynamic namespace", (done) => {
+      const io = new Server(0);
+      io.of(/^\/dynamic-\d+$/);
+      const socket = createClient(io, "/dynamic-101");
+
+      io.on("new_namespace", (namespace) => {
+        expect(namespace.name).to.be("/dynamic-101");
+
+        success(done, io, socket);
+      });
+    });
+
+    it("should handle race conditions with dynamic namespaces (#4136)", (done) => {
+      const io = new Server(0);
+      const counters = {
+        connected: 0,
+        created: 0,
+        events: 0,
+      };
+      const buffer: Function[] = [];
+      io.on("new_namespace", (namespace) => {
+        counters.created++;
+      });
+
+      const handler = () => {
+        if (++counters.events === 2) {
+          expect(counters.created).to.equal(1);
+          success(done, io, one, two);
+        }
+      };
+
+      io.of((name, query, next) => {
+        buffer.push(next);
+        if (buffer.length === 2) {
+          buffer.forEach((next) => next(null, true));
+        }
+      }).on("connection", (socket) => {
+        if (++counters.connected === 2) {
+          io.of("/dynamic-101").emit("message");
+        }
+      });
+
+      let one = createClient(io, "/dynamic-101");
+      let two = createClient(io, "/dynamic-101");
+      one.on("message", handler);
+      two.on("message", handler);
+    });
+  });
+});

test/server-attachment.ts

@@ -0,0 +1,170 @@
+import { Server } from "..";
+import { createServer } from "http";
+import request from "supertest";
+import expect from "expect.js";
+import { getPort, successFn } from "./support/util";
+
+describe("server attachment", () => {
+  describe("http.Server", () => {
+    const clientVersion = require("socket.io-client/package.json").version;
+
+    const testSource = (filename) => (done) => {
+      const srv = createServer();
+      new Server(srv);
+      request(srv)
+        .get("/socket.io/" + filename)
+        .buffer(true)
+        .end((err, res) => {
+          if (err) return done(err);
+          expect(res.headers["content-type"]).to.be("application/javascript");
+          expect(res.headers.etag).to.be('"' + clientVersion + '"');
+          expect(res.headers["x-sourcemap"]).to.be(undefined);
+          expect(res.text).to.match(/engine\.io/);
+          expect(res.status).to.be(200);
+          done();
+        });
+    };
+
+    const testSourceMap = (filename) => (done) => {
+      const srv = createServer();
+      new Server(srv);
+      request(srv)
+        .get("/socket.io/" + filename)
+        .buffer(true)
+        .end((err, res) => {
+          if (err) return done(err);
+          expect(res.headers["content-type"]).to.be("application/json");
+          expect(res.headers.etag).to.be('"' + clientVersion + '"');
+          expect(res.text).to.match(/engine\.io/);
+          expect(res.status).to.be(200);
+          done();
+        });
+    };
+
+    it("should serve client", testSource("socket.io.js"));
+    it(
+      "should serve client with query string",
+      testSource("socket.io.js?buster=" + Date.now())
+    );
+    it("should serve source map", testSourceMap("socket.io.js.map"));
+    it("should serve client (min)", testSource("socket.io.min.js"));
+
+    it("should serve source map (min)", testSourceMap("socket.io.min.js.map"));
+
+    it("should serve client (gzip)", (done) => {
+      const srv = createServer();
+      new Server(srv);
+      request(srv)
+        .get("/socket.io/socket.io.js")
+        .set("accept-encoding", "gzip,br,deflate")
+        .buffer(true)
+        .end((err, res) => {
+          if (err) return done(err);
+          expect(res.headers["content-encoding"]).to.be("gzip");
+          expect(res.status).to.be(200);
+          done();
+        });
+    });
+
+    it(
+      "should serve bundle with msgpack parser",
+      testSource("socket.io.msgpack.min.js")
+    );
+
+    it(
+      "should serve source map for bundle with msgpack parser",
+      testSourceMap("socket.io.msgpack.min.js.map")
+    );
+
+    it("should serve the ESM bundle", testSource("socket.io.esm.min.js"));
+
+    it(
+      "should serve the source map for the ESM bundle",
+      testSourceMap("socket.io.esm.min.js.map")
+    );
+
+    it("should handle 304", (done) => {
+      const srv = createServer();
+      new Server(srv);
+      request(srv)
+        .get("/socket.io/socket.io.js")
+        .set("If-None-Match", '"' + clientVersion + '"')
+        .end((err, res) => {
+          if (err) return done(err);
+          expect(res.statusCode).to.be(304);
+          done();
+        });
+    });
+
+    it("should handle 304", (done) => {
+      const srv = createServer();
+      new Server(srv);
+      request(srv)
+        .get("/socket.io/socket.io.js")
+        .set("If-None-Match", 'W/"' + clientVersion + '"')
+        .end((err, res) => {
+          if (err) return done(err);
+          expect(res.statusCode).to.be(304);
+          done();
+        });
+    });
+
+    it("should not serve static files", (done) => {
+      const srv = createServer();
+      new Server(srv, { serveClient: false });
+      request(srv).get("/socket.io/socket.io.js").expect(400, done);
+    });
+
+    it("should work with #attach", (done) => {
+      const srv = createServer((req, res) => {
+        res.writeHead(404);
+        res.end();
+      });
+      const sockets = new Server();
+      sockets.attach(srv);
+      request(srv)
+        .get("/socket.io/socket.io.js")
+        .end((err, res) => {
+          if (err) return done(err);
+          expect(res.status).to.be(200);
+          done();
+        });
+    });
+
+    it("should work with #attach (and merge options)", () => {
+      const srv = createServer((req, res) => {
+        res.writeHead(404);
+        res.end();
+      });
+      const server = new Server({
+        pingTimeout: 6000,
+      });
+      server.attach(srv, {
+        pingInterval: 24000,
+      });
+      // @ts-ignore
+      expect(server.eio.opts.pingTimeout).to.eql(6000);
+      // @ts-ignore
+      expect(server.eio.opts.pingInterval).to.eql(24000);
+      server.close();
+    });
+  });
+
+  describe("port", () => {
+    it("should be bound", (done) => {
+      const io = new Server(0);
+
+      request(`http://localhost:${getPort(io)}`)
+        .get("/socket.io/socket.io.js")
+        .expect(200, successFn(done, io));
+    });
+
+    it("with listen", (done) => {
+      const io = new Server().listen(0);
+
+      request(`http://localhost:${getPort(io)}`)
+        .get("/socket.io/socket.io.js")
+        .expect(200, successFn(done, io));
+    });
+  });
+});

test/socket-middleware.ts

@@ -0,0 +1,60 @@
+import { Server } from "..";
+import expect from "expect.js";
+import { success, createClient } from "./support/util";
+
+describe("socket middleware", () => {
+  it("should call functions", (done) => {
+    const io = new Server(0);
+    const clientSocket = createClient(io, "/", { multiplex: false });
+
+    clientSocket.emit("join", "woot");
+
+    let run = 0;
+
+    io.on("connection", (socket) => {
+      socket.use((event, next) => {
+        expect(event).to.eql(["join", "woot"]);
+        event.unshift("wrap");
+        run++;
+        next();
+      });
+      socket.use((event, next) => {
+        expect(event).to.eql(["wrap", "join", "woot"]);
+        run++;
+        next();
+      });
+      socket.on("wrap", (data1, data2) => {
+        expect(data1).to.be("join");
+        expect(data2).to.be("woot");
+        expect(run).to.be(2);
+
+        success(done, io, clientSocket);
+      });
+    });
+  });
+
+  it("should pass errors", (done) => {
+    const io = new Server(0);
+    const clientSocket = createClient(io, "/", { multiplex: false });
+
+    clientSocket.emit("join", "woot");
+
+    io.on("connection", (socket) => {
+      socket.use((event, next) => {
+        next(new Error("Authentication error"));
+      });
+      socket.use((event, next) => {
+        done(new Error("should not happen"));
+      });
+      socket.on("join", () => {
+        done(new Error("should not happen"));
+      });
+      socket.on("error", (err) => {
+        expect(err).to.be.an(Error);
+        expect(err.message).to.eql("Authentication error");
+
+        success(done, io, clientSocket);
+      });
+    });
+  });
+});

test/socket.io.test-d.ts

@@ -4,6 +4,7 @@ import type { DefaultEventsMap } from "../lib/typed-events";
 import { createServer } from "http";
 import { expectError, expectType } from "tsd";
 import { Adapter } from "socket.io-adapter";
+import type { DisconnectReason } from "../lib/socket";
 
 // This file is run by tsd, not mocha.
 
@@ -17,10 +18,10 @@ describe("server", () => {
           sio.on("connection", (s) => {
             expectType<Socket<DefaultEventsMap, DefaultEventsMap>>(s);
             s.on("disconnect", (reason) => {
-              expectType<string>(reason);
+              expectType<DisconnectReason>(reason);
             });
             s.on("disconnecting", (reason) => {
-              expectType<string>(reason);
+              expectType<DisconnectReason>(reason);
             });
           });
           sio.on("connect", (s) => {
@@ -208,6 +209,10 @@ describe("server", () => {
         const srv = createServer();
         const sio = new Server<ClientToServerEvents, ServerToClientEvents>(srv);
         srv.listen(() => {
+          sio.emit("helloFromServer", "hi", 1);
+          sio.to("room").emit("helloFromServer", "hi", 1);
+          sio.timeout(1000).emit("helloFromServer", "hi", 1);
+
           sio.on("connection", (s) => {
             s.emit("helloFromServer", "hi", 10);
             done();
@@ -219,6 +224,10 @@ describe("server", () => {
         const srv = createServer();
         const sio = new Server<ClientToServerEvents, ServerToClientEvents>(srv);
         srv.listen(() => {
+          expectError(sio.emit("helloFromClient"));
+          expectError(sio.to("room").emit("helloFromClient"));
+          expectError(sio.timeout(1000).to("room").emit("helloFromClient"));
+
           sio.on("connection", (s) => {
             expectError(s.emit("helloFromClient", "hi"));
             expectError(s.emit("helloFromServer", "hi", 10, "10"));
@@ -233,7 +242,7 @@ describe("server", () => {
     });
   });
 
-  describe("listen and emit event maps", () => {
+  describe("listen and emit event maps for the serverSideEmit method", () => {
     interface ClientToServerEvents {
       helloFromClient: (message: string) => void;
     }

test/support/util.ts

@@ -12,7 +12,7 @@ const i = expect.stringify;
 // add support for Set/Map
 const contain = expect.Assertion.prototype.contain;
 expect.Assertion.prototype.contain = function (...args) {
-  if (typeof this.obj === "object") {
+  if (this.obj instanceof Set || this.obj instanceof Map) {
     args.forEach((obj) => {
       this.assert(
         this.obj.has(obj),
@@ -31,16 +31,50 @@ expect.Assertion.prototype.contain = function (...args) {
 
 export function createClient(
   io: Server,
-  nsp: string,
-  opts?: ManagerOptions & SocketOptions
+  nsp: string = "/",
+  opts?: Partial<ManagerOptions & SocketOptions>
 ): ClientSocket {
   // @ts-ignore
   const port = io.httpServer.address().port;
   return ioc(`http://localhost:${port}${nsp}`, opts);
 }
 
-export function success(done: Function, io: Server, client: ClientSocket) {
+export function success(
+  done: Function,
+  io: Server,
+  ...clients: ClientSocket[]
+) {
   io.close();
-  client.disconnect();
+  clients.forEach((client) => client.disconnect());
   done();
 }
+
+export function successFn(
+  done: () => void,
+  sio: Server,
+  ...clientSockets: ClientSocket[]
+) {
+  return () => success(done, sio, ...clientSockets);
+}
+
+export function getPort(io: Server): number {
+  // @ts-ignore
+  return io.httpServer.address().port;
+}
+
+export function createPartialDone(count: number, done: (err?: Error) => void) {
+  let i = 0;
+  return () => {
+    if (++i === count) {
+      done();
+    } else if (i > count) {
+      done(new Error(`partialDone() called too many times: ${i} > ${count}`));
+    }
+  };
+}
+
+export function waitFor(emitter, event) {
+  return new Promise((resolve) => {
+    emitter.once(event, resolve);
+  });
+}

test/utility-methods.ts

@@ -6,26 +6,10 @@ import expect from "expect.js";
 import type { AddressInfo } from "net";
 
 import "./support/util";
+import { createPartialDone } from "./support/util";
 
 const SOCKETS_COUNT = 3;
 
-const createPartialDone = (
-  count: number,
-  done: () => void,
-  callback?: () => void
-) => {
-  let i = 0;
-  return () => {
-    i++;
-    if (i === count) {
-      done();
-      if (callback) {
-        callback();
-      }
-    }
-  };
-};
-
 class DummyAdapter extends Adapter {
   fetchSockets(opts: BroadcastOptions): Promise<any[]> {
     return Promise.resolve([
@@ -49,7 +33,7 @@ class DummyAdapter extends Adapter {
   }
 }
 
-describe("socket.io", () => {
+describe("utility methods", () => {
   let io: Server, clientSockets: ClientSocket[], serverSockets: Socket[];
   beforeEach((done) => {
     const srv = createServer();
@@ -59,7 +43,12 @@ describe("socket.io", () => {
 
       clientSockets = [];
       for (let i = 0; i < SOCKETS_COUNT; i++) {
-        clientSockets.push(ioc(`http://localhost:${port}`));
+        clientSockets.push(
+          ioc(`http://localhost:${port}`, {
+            // FIXME needed so that clients are properly closed
+            transports: ["websocket"],
+          })
+        );
       }
 
       serverSockets = [];
@@ -77,100 +66,99 @@ describe("socket.io", () => {
     clientSockets.forEach((socket) => socket.disconnect());
   });
 
-  describe("utility methods", () => {
-    describe("fetchSockets", () => {
-      it("returns all socket instances", async () => {
-        const sockets = await io.fetchSockets();
-        expect(sockets.length).to.eql(3);
-      });
+  describe("fetchSockets", () => {
+    it("returns all socket instances", async () => {
+      const sockets = await io.fetchSockets();
+      expect(sockets.length).to.eql(3);
+    });
 
-      it("returns all socket instances in the given room", async () => {
-        serverSockets[0].join(["room1", "room2"]);
-        serverSockets[1].join("room1");
-        serverSockets[2].join("room2");
-        const sockets = await io.in("room1").fetchSockets();
-        expect(sockets.length).to.eql(2);
-      });
+    it("returns all socket instances in the given room", async () => {
+      serverSockets[0].join(["room1", "room2"]);
+      serverSockets[1].join("room1");
+      serverSockets[2].join("room2");
+      const sockets = await io.in("room1").fetchSockets();
+      expect(sockets.length).to.eql(2);
+    });
 
-      it("works with a custom adapter", async () => {
-        io.adapter(DummyAdapter);
-        const sockets = await io.fetchSockets();
-        expect(sockets.length).to.eql(1);
-        const remoteSocket = sockets[0];
-        expect(remoteSocket.id).to.eql("42");
-        expect(remoteSocket.rooms).to.contain("42", "room1");
-        expect(remoteSocket.data).to.eql({ username: "john" });
+    it("works with a custom adapter", async () => {
+      io.adapter(DummyAdapter);
+      const sockets = await io.fetchSockets();
+      expect(sockets.length).to.eql(1);
+      const remoteSocket = sockets[0];
+      expect(remoteSocket.id).to.eql("42");
+      expect(remoteSocket.rooms).to.contain("42", "room1");
+      expect(remoteSocket.data).to.eql({ username: "john" });
+    });
+  });
+
+  describe("socketsJoin", () => {
+    it("makes all socket instances join the given room", () => {
+      io.socketsJoin("room1");
+      serverSockets.forEach((socket) => {
+        expect(socket.rooms).to.contain("room1");
       });
     });
 
-    describe("socketsJoin", () => {
-      it("makes all socket instances join the given room", () => {
-        io.socketsJoin("room1");
-        serverSockets.forEach((socket) => {
-          expect(socket.rooms).to.contain("room1");
-        });
-      });
+    it("makes all socket instances in a room join the given room", () => {
+      serverSockets[0].join(["room1", "room2"]);
+      serverSockets[1].join("room1");
+      serverSockets[2].join("room2");
+      io.in("room1").socketsJoin("room3");
+      expect(serverSockets[0].rooms).to.contain("room3");
+      expect(serverSockets[1].rooms).to.contain("room3");
+      expect(serverSockets[2].rooms).to.not.contain("room3");
+    });
+  });
 
-      it("makes all socket instances in a room join the given room", () => {
-        serverSockets[0].join(["room1", "room2"]);
-        serverSockets[1].join("room1");
-        serverSockets[2].join("room2");
-        io.in("room1").socketsJoin("room3");
-        expect(serverSockets[0].rooms).to.contain("room3");
-        expect(serverSockets[1].rooms).to.contain("room3");
-        expect(serverSockets[2].rooms).to.not.contain("room3");
-      });
+  describe("socketsLeave", () => {
+    it("makes all socket instances leave the given room", () => {
+      serverSockets[0].join(["room1", "room2"]);
+      serverSockets[1].join("room1");
+      serverSockets[2].join("room2");
+      io.socketsLeave("room1");
+      expect(serverSockets[0].rooms).to.contain("room2");
+      expect(serverSockets[0].rooms).to.not.contain("room1");
+      expect(serverSockets[1].rooms).to.not.contain("room1");
     });
 
-    describe("socketsLeave", () => {
-      it("makes all socket instances leave the given room", () => {
-        serverSockets[0].join(["room1", "room2"]);
-        serverSockets[1].join("room1");
-        serverSockets[2].join("room2");
-        io.socketsLeave("room1");
-        expect(serverSockets[0].rooms).to.contain("room2");
-        expect(serverSockets[0].rooms).to.not.contain("room1");
-        expect(serverSockets[1].rooms).to.not.contain("room1");
-      });
+    it("makes all socket instances in a room leave the given room", () => {
+      serverSockets[0].join(["room1", "room2"]);
+      serverSockets[1].join("room1");
+      serverSockets[2].join("room2");
+      io.in("room2").socketsLeave("room1");
+      expect(serverSockets[0].rooms).to.contain("room2");
+      expect(serverSockets[0].rooms).to.not.contain("room1");
+      expect(serverSockets[1].rooms).to.contain("room1");
+    });
+  });
 
-      it("makes all socket instances in a room leave the given room", () => {
-        serverSockets[0].join(["room1", "room2"]);
-        serverSockets[1].join("room1");
-        serverSockets[2].join("room2");
-        io.in("room2").socketsLeave("room1");
-        expect(serverSockets[0].rooms).to.contain("room2");
-        expect(serverSockets[0].rooms).to.not.contain("room1");
-        expect(serverSockets[1].rooms).to.contain("room1");
-      });
+  describe("disconnectSockets", () => {
+    it("makes all socket instances disconnect", (done) => {
+      io.disconnectSockets(true);
+
+      const partialDone = createPartialDone(3, done);
+
+      clientSockets[0].on("disconnect", partialDone);
+      clientSockets[1].on("disconnect", partialDone);
+      clientSockets[2].on("disconnect", partialDone);
     });
 
-    describe("disconnectSockets", () => {
-      it("makes all socket instances disconnect", (done) => {
-        io.disconnectSockets(true);
+    it("makes all socket instances in a room disconnect", (done) => {
+      serverSockets[0].join(["room1", "room2"]);
+      serverSockets[1].join("room1");
+      serverSockets[2].join("room2");
+      io.in("room2").disconnectSockets(true);
 
-        const partialDone = createPartialDone(3, done);
-
-        clientSockets[0].on("disconnect", partialDone);
-        clientSockets[1].on("disconnect", partialDone);
-        clientSockets[2].on("disconnect", partialDone);
+      const partialDone = createPartialDone(2, () => {
+        clientSockets[1].off("disconnect");
+        done();
       });
 
-      it("makes all socket instances in a room disconnect", (done) => {
-        serverSockets[0].join(["room1", "room2"]);
-        serverSockets[1].join("room1");
-        serverSockets[2].join("room2");
-        io.in("room2").disconnectSockets(true);
-
-        const partialDone = createPartialDone(2, done, () => {
-          clientSockets[1].off("disconnect");
-        });
-
-        clientSockets[0].on("disconnect", partialDone);
-        clientSockets[1].on("disconnect", () => {
-          done(new Error("should not happen"));
-        });
-        clientSockets[2].on("disconnect", partialDone);
+      clientSockets[0].on("disconnect", partialDone);
+      clientSockets[1].on("disconnect", () => {
+        done(new Error("should not happen"));
       });
+      clientSockets[2].on("disconnect", partialDone);
     });
   });
 });

test/uws.ts

@@ -1,4 +1,8 @@
-import { App, us_socket_local_port } from "uWebSockets.js";
+import {
+  App,
+  us_socket_local_port,
+  us_listen_socket_close,
+} from "uWebSockets.js";
 import { Server } from "..";
 import { io as ioc, Socket as ClientSocket } from "socket.io-client";
 import request from "supertest";
@@ -19,6 +23,7 @@ const shouldNotHappen = (done) => () => done(new Error("should not happen"));
 
 describe("socket.io with uWebSocket.js-based engine", () => {
   let io: Server,
+    uwsSocket: any,
     port: number,
     client: ClientSocket,
     clientWSOnly: ClientSocket,
@@ -33,6 +38,7 @@ describe("socket.io with uWebSocket.js-based engine", () => {
     io.of("/custom");
 
     app.listen(0, (listenSocket) => {
+      uwsSocket = listenSocket;
       port = us_socket_local_port(listenSocket);
 
       client = ioc(`http://localhost:${port}`);
@@ -54,6 +60,8 @@ describe("socket.io with uWebSocket.js-based engine", () => {
 
   afterEach(() => {
     io.close();
+    us_listen_socket_close(uwsSocket);
+
     client.disconnect();
     clientWSOnly.disconnect();
     clientPollingOnly.disconnect();
@@ -178,6 +186,12 @@ describe("socket.io with uWebSocket.js-based engine", () => {
     io.to("room1").emit("hello");
   });
 
+  it("should not crash when socket is disconnected before the upgrade", (done) => {
+    client.on("disconnect", () => done());
+
+    io.of("/").sockets.get(client.id)!.disconnect();
+  });
+
   it("should serve static files", (done) => {
     const clientVersion = require("socket.io-client/package.json").version;
 

test/v2-compatibility.ts

@@ -0,0 +1,64 @@
+import { Server, Socket } from "..";
+import expect from "expect.js";
+import { success, getPort, waitFor } from "./support/util";
+import * as io_v2 from "socket.io-client-v2";
+
+describe("v2 compatibility", () => {
+  it("should connect if `allowEIO3` is true", (done) => {
+    const io = new Server(0, {
+      allowEIO3: true,
+    });
+
+    const clientSocket = io_v2.connect(`http://localhost:${getPort(io)}`, {
+      multiplex: false,
+    });
+
+    Promise.all([
+      waitFor(io, "connection"),
+      waitFor(clientSocket, "connect"),
+    ]).then(([socket]) => {
+      expect((socket as Socket).id).to.eql(clientSocket.id);
+
+      success(done, io, clientSocket);
+    });
+  });
+
+  it("should be able to connect to a namespace with a query", (done) => {
+    const io = new Server(0, {
+      allowEIO3: true,
+    });
+
+    const clientSocket = io_v2.connect(
+      `http://localhost:${getPort(io)}/the-namespace`,
+      {
+        multiplex: false,
+      }
+    );
+    clientSocket.query = { test: "123" };
+
+    Promise.all([
+      waitFor(io.of("/the-namespace"), "connection"),
+      waitFor(clientSocket, "connect"),
+    ]).then(([socket]) => {
+      expect((socket as Socket).handshake.auth).to.eql({ test: "123" });
+
+      success(done, io, clientSocket);
+    });
+  });
+
+  it("should not connect if `allowEIO3` is false (default)", (done) => {
+    const io = new Server(0);
+
+    const clientSocket = io_v2.connect(`http://localhost:${getPort(io)}`, {
+      multiplex: false,
+    });
+
+    clientSocket.on("connect", () => {
+      done(new Error("should not happen"));
+    });
+
+    clientSocket.on("connect_error", () => {
+      success(done, io, clientSocket);
+    });
+  });
+});