chore(release): 3.1.2

Diff: https://github.com/socketio/socket.io/compare/3.1.1...3.1.2

.github/ISSUE_TEMPLATE.md

@@ -1,32 +0,0 @@
-
-**Note**: for support questions, please use one of these channels: [stackoverflow](http://stackoverflow.com/questions/tagged/socket.io) or [slack](https://socketio.slack.com)
-
-For bug reports and feature requests for the **Swift client**, please open an issue [there](https://github.com/socketio/socket.io-client-swift).
-
-For bug reports and feature requests for the **Java client**, please open an issue [there](https://github.com/socketio/socket.io-client-java).
-
-### You want to:
-
-* [x] report a *bug*
-* [ ] request a *feature*
-
-### Current behaviour
-
-*What is actually happening?*
-
-### Steps to reproduce (if the current behaviour is a bug)
-
-**Note**: the best way (and by that we mean **the only way**) to get a quick answer is to provide a failing test case by forking the following [fiddle](https://github.com/socketio/socket.io-fiddle).
-
-### Expected behaviour
-
-*What is expected?*
-
-### Setup
-- OS:
-- browser:
-- socket.io version:
-
-### Other information (e.g. stacktraces, related issues, suggestions how to fix)
-
-

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,61 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: 'bug'
+assignees: ''
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+
+Please fill the following code example:
+
+Socket.IO server version: `x.y.z`
+
+*Server*
+
+```js
+import { Server } from "socket.io";
+
+const io = new Server(3000, {});
+
+io.on("connection", (socket) => {
+  console.log(`connect ${socket.id}`);
+
+  socket.on("disconnect", () => {
+    console.log(`disconnect ${socket.id}`);
+  });
+});
+```
+
+Socket.IO client version: `x.y.z`
+
+*Client*
+
+```js
+import { io } from "socket.io-client";
+
+const socket = io("ws://localhost:3000/", {});
+
+socket.on("connect", () => {
+  console.log(`connect ${socket.id}`);
+});
+
+socket.on("disconnect", () => {
+  console.log("disconnect");
+});
+```
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Platform:**
+ - Device: [e.g. Samsung S8]
+ - OS: [e.g. Android 9.2]
+
+**Additional context**
+Add any other context about the problem here.

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,5 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Ask a Question
+    url: https://github.com/socketio/socket.io/discussions/new?category=q-a
+    about: Ask the community for help

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,20 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+title: ''
+labels: 'enhancement'
+assignees: ''
+
+---
+
+**Is your feature request related to a problem? Please describe.**
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+
+**Describe the solution you'd like**
+A clear and concise description of what you want to happen.
+
+**Describe alternatives you've considered**
+A clear and concise description of any alternative solutions or features you've considered.
+
+**Additional context**
+Add any other context or screenshots about the feature request here.

.github/PULL_REQUEST_TEMPLATE.md

@@ -7,10 +7,10 @@
 * [ ] a code change that improves performance
 * [ ] other
 
-### Current behaviour
+### Current behavior
 
 
-### New behaviour
+### New behavior
 
 
 ### Other information (e.g. related issues)

.github/workflows/ci.yml

@@ -0,0 +1,26 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+  schedule:
+    - cron: '0 0 * * 0'
+
+jobs:
+  test-node:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [10.x, 12.x, 14.x, 15.x]
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v1
+        with:
+          node-version: ${{ matrix.node-version }}
+      - run: npm ci
+      - run: npm test
+        env:
+          CI: true

.replit

@@ -0,0 +1,2 @@
+language = "nodejs"
+run = "npm start"

.travis.yml

@@ -1,10 +0,0 @@
-language: node_js
-sudo: false
-node_js:
-  - '10'
-  - '12'
-  - '14'
-notifications:
-  irc: "irc.freenode.org#socket.io"
-git:
-  depth: 1

CHANGELOG.md

@@ -1,3 +1,56 @@
+## [3.1.2](https://github.com/socketio/socket.io/compare/3.1.1...3.1.2) (2021-02-26)
+
+
+### Bug Fixes
+
+* ignore packets received after disconnection ([494c64e](https://github.com/socketio/socket.io/commit/494c64e44f645cbd24c645f1186d203789e84af0))
+
+
+## [3.1.1](https://github.com/socketio/socket.io/compare/3.1.0...3.1.1) (2021-02-03)
+
+
+### Bug Fixes
+
+* properly parse the CONNECT packet in v2 compatibility mode ([6f4bd7f](https://github.com/socketio/socket.io/commit/6f4bd7f8e7c41a075a8014565330a77c38b03a8d))
+* **typings:** add return types and general-case overload signatures ([#3776](https://github.com/socketio/socket.io/issues/3776)) ([9e8f288](https://github.com/socketio/socket.io/commit/9e8f288ca9f14f91064b8d3cce5946f7d23d407c))
+* **typings:** update the types of "query", "auth" and "headers" ([4f2e9a7](https://github.com/socketio/socket.io/commit/4f2e9a716d9835b550c8fd9a9b429ebf069c2895))
+
+
+# [3.1.0](https://github.com/socketio/socket.io/compare/3.0.5...3.1.0) (2021-01-15)
+
+
+### Features
+
+* confirm a weak but matching ETag ([#3485](https://github.com/socketio/socket.io/issues/3485)) ([161091d](https://github.com/socketio/socket.io/commit/161091dd4c9e1b1610ac3d45d964195e63d92b94))
+* **esm:** export the Namespace and Socket class ([#3699](https://github.com/socketio/socket.io/issues/3699)) ([233650c](https://github.com/socketio/socket.io/commit/233650c22209708b5fccc4349c38d2fa1b465d8f))
+* add support for Socket.IO v2 clients ([9925746](https://github.com/socketio/socket.io/commit/9925746c8ee3a6522bd640b5d586c83f04f2f1ba))
+* add room events ([155fa63](https://github.com/socketio/socket.io-adapter/commit/155fa6333a504036e99a33667dc0397f6aede25e))
+
+
+### Bug Fixes
+
+* allow integers as event names ([1c220dd](https://github.com/socketio/socket.io-parser/commit/1c220ddbf45ea4b44bc8dbf6f9ae245f672ba1b9))
+
+
+## [3.0.5](https://github.com/socketio/socket.io/compare/3.0.4...3.0.5) (2021-01-05)
+
+
+### Bug Fixes
+
+* properly clear timeout on connection failure ([170b739](https://github.com/socketio/socket.io/commit/170b739f147cb6c92b423729b877e242e376927d))
+
+
+### Reverts
+
+* restore the socket middleware functionality ([bf54327](https://github.com/socketio/socket.io/commit/bf5432742158e4d5ba2722cff4a614967dffa5b9))
+
+
+## [3.0.4](https://github.com/socketio/socket.io/compare/3.0.3...3.0.4) (2020-12-07)
+
+
+## [3.0.3](https://github.com/socketio/socket.io/compare/3.0.2...3.0.3) (2020-11-19)
+
+
 ## [3.0.2](https://github.com/socketio/socket.io/compare/3.0.1...3.0.2) (2020-11-17)
 
 

Readme.md

@@ -1,8 +1,7 @@
-
 # socket.io
-
+[![Run on Repl.it](https://repl.it/badge/github/socketio/socket.io)](https://repl.it/github/socketio/socket.io)
 [![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://secure.travis-ci.org/socketio/socket.io.svg?branch=master)](https://travis-ci.org/socketio/socket.io)
+[![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)
@@ -22,6 +21,8 @@ Some implementations in other languages are also available:
 - [C++](https://github.com/socketio/socket.io-client-cpp)
 - [Swift](https://github.com/socketio/socket.io-client-swift)
 - [Dart](https://github.com/rikulo/socket.io-client-dart)
+- [Python](https://github.com/miguelgrinberg/python-socketio)
+- [.Net](https://github.com/Quobject/SocketIoClientDotNet)
 
 Its main features are:
 
@@ -35,7 +36,7 @@ For this purpose, it relies on [Engine.IO](https://github.com/socketio/engine.io
 
 #### Auto-reconnection support
 
-Unless instructed otherwise a disconnected client will try to reconnect forever, until the server is available again. Please see the available reconnection options [here](https://github.com/socketio/socket.io-client/blob/master/docs/API.md#new-managerurl-options).
+Unless instructed otherwise a disconnected client will try to reconnect forever, until the server is available again. Please see the available reconnection options [here](https://socket.io/docs/v3/client-api/#new-Manager-url-options).
 
 #### Disconnection detection
 
@@ -84,7 +85,11 @@ This is a useful feature to send notifications to a group of users, or to a give
 ## Installation
 
 ```bash
+// with npm
 npm install socket.io
+
+// with yarn
+yarn add socket.io
 ```
 
 ## How to use

examples/angular-todomvc/.browserslistrc

@@ -0,0 +1,17 @@
+# This file is used by the build system to adjust CSS and JS output to support the specified browsers below.
+# For additional information regarding the format and rule options, please see:
+# https://github.com/browserslist/browserslist#queries
+
+# For the full list of supported browsers by the Angular framework, please see:
+# https://angular.io/guide/browser-support
+
+# You can see what browsers were selected by your queries by running:
+#   npx browserslist
+
+last 1 Chrome version
+last 1 Firefox version
+last 2 Edge major versions
+last 2 Safari major versions
+last 2 iOS major versions
+Firefox ESR
+not IE 11 # Angular supports IE 11 only as an opt-in. To opt-in, remove the 'not' prefix on this line.

examples/angular-todomvc/.editorconfig

@@ -0,0 +1,16 @@
+# Editor configuration, see https://editorconfig.org
+root = true
+
+[*]
+charset = utf-8
+indent_style = space
+indent_size = 2
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.ts]
+quote_type = single
+
+[*.md]
+max_line_length = off
+trim_trailing_whitespace = false

examples/angular-todomvc/.gitignore

@@ -0,0 +1,46 @@
+# See http://help.github.com/ignore-files/ for more about ignoring files.
+
+# compiled output
+/dist
+/tmp
+/out-tsc
+# Only exists if Bazel was run
+/bazel-out
+
+# dependencies
+/node_modules
+
+# profiling files
+chrome-profiler-events*.json
+speed-measure-plugin*.json
+
+# IDEs and editors
+/.idea
+.project
+.classpath
+.c9/
+*.launch
+.settings/
+*.sublime-workspace
+
+# IDE - VSCode
+.vscode/*
+!.vscode/settings.json
+!.vscode/tasks.json
+!.vscode/launch.json
+!.vscode/extensions.json
+.history/*
+
+# misc
+/.sass-cache
+/connect.lock
+/coverage
+/libpeerconnection.log
+npm-debug.log
+yarn-error.log
+testem.log
+/typings
+
+# System Files
+.DS_Store
+Thumbs.db

examples/angular-todomvc/README.md

@@ -0,0 +1,35 @@
+# Angular TodoMVC + Socket.IO
+
+This project was generated with [Angular CLI](https://github.com/angular/angular-cli) version 11.0.4.
+
+Inspired from the [TodoMVC](http://todomvc.com/) [angular example](https://github.com/tastejs/todomvc/tree/master/examples/angular2).
+
+![demo](assets/demo.gif)
+
+## Development server
+
+Run `ng serve` for a dev server. Navigate to `http://localhost:4200/`. The app will automatically reload if you change any of the source files.
+
+## Socket.IO server
+
+Run `npm run start:server` to start the Socket.IO server.
+
+## Code scaffolding
+
+Run `ng generate component component-name` to generate a new component. You can also use `ng generate directive|pipe|service|class|guard|interface|enum|module`.
+
+## Build
+
+Run `ng build` to build the project. The build artifacts will be stored in the `dist/` directory. Use the `--prod` flag for a production build.
+
+## Running unit tests
+
+Run `ng test` to execute the unit tests via [Karma](https://karma-runner.github.io).
+
+## Running end-to-end tests
+
+Run `ng e2e` to execute the end-to-end tests via [Protractor](http://www.protractortest.org/).
+
+## Further help
+
+To get more help on the Angular CLI use `ng help` or go check out the [Angular CLI Overview and Command Reference](https://angular.io/cli) page.

examples/angular-todomvc/angular.json

@@ -0,0 +1,128 @@
+{
+  "$schema": "./node_modules/@angular/cli/lib/config/schema.json",
+  "version": 1,
+  "newProjectRoot": "projects",
+  "projects": {
+    "angular-todomvc": {
+      "projectType": "application",
+      "schematics": {
+        "@schematics/angular:application": {
+          "strict": true
+        }
+      },
+      "root": "",
+      "sourceRoot": "src",
+      "prefix": "app",
+      "architect": {
+        "build": {
+          "builder": "@angular-devkit/build-angular:browser",
+          "options": {
+            "outputPath": "dist/angular-todomvc",
+            "index": "src/index.html",
+            "main": "src/main.ts",
+            "polyfills": "src/polyfills.ts",
+            "tsConfig": "tsconfig.app.json",
+            "aot": true,
+            "assets": [
+              "src/favicon.ico",
+              "src/assets"
+            ],
+            "styles": [
+              "src/styles.css"
+            ],
+            "scripts": []
+          },
+          "configurations": {
+            "production": {
+              "fileReplacements": [
+                {
+                  "replace": "src/environments/environment.ts",
+                  "with": "src/environments/environment.prod.ts"
+                }
+              ],
+              "optimization": true,
+              "outputHashing": "all",
+              "sourceMap": false,
+              "namedChunks": false,
+              "extractLicenses": true,
+              "vendorChunk": false,
+              "buildOptimizer": true,
+              "budgets": [
+                {
+                  "type": "initial",
+                  "maximumWarning": "500kb",
+                  "maximumError": "1mb"
+                },
+                {
+                  "type": "anyComponentStyle",
+                  "maximumWarning": "2kb",
+                  "maximumError": "4kb"
+                }
+              ]
+            }
+          }
+        },
+        "serve": {
+          "builder": "@angular-devkit/build-angular:dev-server",
+          "options": {
+            "browserTarget": "angular-todomvc:build"
+          },
+          "configurations": {
+            "production": {
+              "browserTarget": "angular-todomvc:build:production"
+            }
+          }
+        },
+        "extract-i18n": {
+          "builder": "@angular-devkit/build-angular:extract-i18n",
+          "options": {
+            "browserTarget": "angular-todomvc:build"
+          }
+        },
+        "test": {
+          "builder": "@angular-devkit/build-angular:karma",
+          "options": {
+            "main": "src/test.ts",
+            "polyfills": "src/polyfills.ts",
+            "tsConfig": "tsconfig.spec.json",
+            "karmaConfig": "karma.conf.js",
+            "assets": [
+              "src/favicon.ico",
+              "src/assets"
+            ],
+            "styles": [
+              "src/styles.css"
+            ],
+            "scripts": []
+          }
+        },
+        "lint": {
+          "builder": "@angular-devkit/build-angular:tslint",
+          "options": {
+            "tsConfig": [
+              "tsconfig.app.json",
+              "tsconfig.spec.json",
+              "e2e/tsconfig.json"
+            ],
+            "exclude": [
+              "**/node_modules/**"
+            ]
+          }
+        },
+        "e2e": {
+          "builder": "@angular-devkit/build-angular:protractor",
+          "options": {
+            "protractorConfig": "e2e/protractor.conf.js",
+            "devServerTarget": "angular-todomvc:serve"
+          },
+          "configurations": {
+            "production": {
+              "devServerTarget": "angular-todomvc:serve:production"
+            }
+          }
+        }
+      }
+    }
+  },
+  "defaultProject": "angular-todomvc"
+}

examples/angular-todomvc/e2e/protractor.conf.js

@@ -0,0 +1,37 @@
+// @ts-check
+// Protractor configuration file, see link for more information
+// https://github.com/angular/protractor/blob/master/lib/config.ts
+
+const { SpecReporter, StacktraceOption } = require('jasmine-spec-reporter');
+
+/**
+ * @type { import("protractor").Config }
+ */
+exports.config = {
+  allScriptsTimeout: 11000,
+  specs: [
+    './src/**/*.e2e-spec.ts'
+  ],
+  capabilities: {
+    browserName: 'chrome'
+  },
+  directConnect: true,
+  SELENIUM_PROMISE_MANAGER: false,
+  baseUrl: 'http://localhost:4200/',
+  framework: 'jasmine',
+  jasmineNodeOpts: {
+    showColors: true,
+    defaultTimeoutInterval: 30000,
+    print: function() {}
+  },
+  onPrepare() {
+    require('ts-node').register({
+      project: require('path').join(__dirname, './tsconfig.json')
+    });
+    jasmine.getEnv().addReporter(new SpecReporter({
+      spec: {
+        displayStacktrace: StacktraceOption.PRETTY
+      }
+    }));
+  }
+};

examples/angular-todomvc/e2e/src/app.e2e-spec.ts

@@ -0,0 +1,23 @@
+import { AppPage } from './app.po';
+import { browser, logging } from 'protractor';
+
+describe('workspace-project App', () => {
+  let page: AppPage;
+
+  beforeEach(() => {
+    page = new AppPage();
+  });
+
+  it('should display welcome message', async () => {
+    await page.navigateTo();
+    expect(await page.getTitleText()).toEqual('angular-todomvc app is running!');
+  });
+
+  afterEach(async () => {
+    // Assert that there are no errors emitted from the browser
+    const logs = await browser.manage().logs().get(logging.Type.BROWSER);
+    expect(logs).not.toContain(jasmine.objectContaining({
+      level: logging.Level.SEVERE,
+    } as logging.Entry));
+  });
+});

examples/angular-todomvc/e2e/src/app.po.ts

@@ -0,0 +1,11 @@
+import { browser, by, element } from 'protractor';
+
+export class AppPage {
+  async navigateTo(): Promise<unknown> {
+    return browser.get(browser.baseUrl);
+  }
+
+  async getTitleText(): Promise<string> {
+    return element(by.css('app-root .content span')).getText();
+  }
+}

examples/angular-todomvc/e2e/tsconfig.json

@@ -0,0 +1,13 @@
+/* To learn more about this file see: https://angular.io/config/tsconfig. */
+{
+  "extends": "../tsconfig.json",
+  "compilerOptions": {
+    "outDir": "../out-tsc/e2e",
+    "module": "commonjs",
+    "target": "es2018",
+    "types": [
+      "jasmine",
+      "node"
+    ]
+  }
+}

examples/angular-todomvc/karma.conf.js

@@ -0,0 +1,44 @@
+// Karma configuration file, see link for more information
+// https://karma-runner.github.io/1.0/config/configuration-file.html
+
+module.exports = function (config) {
+  config.set({
+    basePath: '',
+    frameworks: ['jasmine', '@angular-devkit/build-angular'],
+    plugins: [
+      require('karma-jasmine'),
+      require('karma-chrome-launcher'),
+      require('karma-jasmine-html-reporter'),
+      require('karma-coverage'),
+      require('@angular-devkit/build-angular/plugins/karma')
+    ],
+    client: {
+      jasmine: {
+        // you can add configuration options for Jasmine here
+        // the possible options are listed at https://jasmine.github.io/api/edge/Configuration.html
+        // for example, you can disable the random execution with `random: false`
+        // or set a specific seed with `seed: 4321`
+      },
+      clearContext: false // leave Jasmine Spec Runner output visible in browser
+    },
+    jasmineHtmlReporter: {
+      suppressAll: true // removes the duplicated traces
+    },
+    coverageReporter: {
+      dir: require('path').join(__dirname, './coverage/angular-todomvc'),
+      subdir: '.',
+      reporters: [
+        { type: 'html' },
+        { type: 'text-summary' }
+      ]
+    },
+    reporters: ['progress', 'kjhtml'],
+    port: 9876,
+    colors: true,
+    logLevel: config.LOG_INFO,
+    autoWatch: true,
+    browsers: ['Chrome'],
+    singleRun: false,
+    restartOnFileChange: true
+  });
+};

examples/angular-todomvc/package.json

@@ -0,0 +1,48 @@
+{
+  "name": "angular-todomvc",
+  "version": "0.0.0",
+  "scripts": {
+    "ng": "ng",
+    "start": "ng serve",
+    "build": "ng build",
+    "test": "ng test",
+    "lint": "ng lint",
+    "e2e": "ng e2e",
+    "start:server": "ts-node -O '{\"module\":\"commonjs\"}' server.ts"
+  },
+  "private": true,
+  "dependencies": {
+    "@angular/animations": "~11.0.4",
+    "@angular/common": "~11.0.4",
+    "@angular/compiler": "~11.0.4",
+    "@angular/core": "~11.0.4",
+    "@angular/forms": "~11.0.4",
+    "@angular/platform-browser": "~11.0.4",
+    "@angular/platform-browser-dynamic": "~11.0.4",
+    "@angular/router": "~11.0.4",
+    "rxjs": "~6.6.0",
+    "socket.io": "^3.0.4",
+    "socket.io-client": "^3.0.4",
+    "tslib": "^2.0.0",
+    "zone.js": "~0.10.2"
+  },
+  "devDependencies": {
+    "@angular-devkit/build-angular": "~0.1100.4",
+    "@angular/cli": "~11.0.4",
+    "@angular/compiler-cli": "~11.0.4",
+    "@types/jasmine": "~3.6.0",
+    "@types/node": "^12.11.1",
+    "codelyzer": "^6.0.0",
+    "jasmine-core": "~3.6.0",
+    "jasmine-spec-reporter": "~5.0.0",
+    "karma": "~5.1.0",
+    "karma-chrome-launcher": "~3.1.0",
+    "karma-coverage": "~2.0.3",
+    "karma-jasmine": "~4.0.0",
+    "karma-jasmine-html-reporter": "^1.5.0",
+    "protractor": "~7.0.0",
+    "ts-node": "~8.3.0",
+    "tslint": "~6.1.0",
+    "typescript": "~4.0.2"
+  }
+}

examples/angular-todomvc/server.ts

@@ -0,0 +1,28 @@
+import { Server, Socket } from "socket.io";
+
+const io = new Server(8080, {
+  cors: {
+    origin: "http://localhost:4200",
+    methods: ["GET", "POST"]
+  }
+});
+
+interface Todo {
+  completed: boolean;
+  editing: boolean;
+  title: string;
+}
+
+let todos: Array<Todo> = [];
+
+io.on("connect", (socket: Socket) => {
+    socket.emit("todos", todos);
+
+    // note: we could also create a CRUD (create/read/update/delete) service for the todo list
+    socket.on("update-store", (updatedTodos) => {
+      // store it locally
+      todos = updatedTodos;
+      // broadcast to everyone but the sender
+      socket.broadcast.emit("todos", todos);
+    });
+});

examples/angular-todomvc/src/app/app.component.html

@@ -0,0 +1,23 @@
+<section class="todoapp">
+  <header class="header">
+    <h1>todos</h1>
+    <input class="new-todo" placeholder="What needs to be done?" autofocus="" [(ngModel)]="newTodoText" (keyup.enter)="addTodo()">
+  </header>
+  <section class="main" *ngIf="todoStore.todos.length > 0">
+    <input id="toggle-all" class="toggle-all" type="checkbox" *ngIf="todoStore.todos.length" #toggleall [checked]="todoStore.allCompleted()" (click)="todoStore.setAllTo(toggleall.checked)">
+    <ul class="todo-list">
+      <li *ngFor="let todo of todoStore.todos" [class.completed]="todo.completed" [class.editing]="todo.editing">
+        <div class="view">
+          <input class="toggle" type="checkbox" (click)="toggleCompletion(todo)" [checked]="todo.completed">
+          <label (dblclick)="editTodo(todo)">{{todo.title}}</label>
+          <button class="destroy" (click)="remove(todo)"></button>
+        </div>
+        <input class="edit" *ngIf="todo.editing" [value]="todo.title" #editedtodo (blur)="stopEditing(todo, editedtodo.value)" (keyup.enter)="updateEditingTodo(todo, editedtodo.value)" (keyup.escape)="cancelEditingTodo(todo)">
+      </li>
+    </ul>
+  </section>
+  <footer class="footer" *ngIf="todoStore.todos.length > 0">
+    <span class="todo-count"><strong>{{todoStore.getRemaining().length}}</strong> {{todoStore.getRemaining().length == 1 ? 'item' : 'items'}} left</span>
+    <button class="clear-completed" *ngIf="todoStore.getCompleted().length > 0" (click)="removeCompleted()">Clear completed</button>
+  </footer>
+</section>

examples/angular-todomvc/src/app/app.component.spec.ts

@@ -0,0 +1,31 @@
+import { TestBed } from '@angular/core/testing';
+import { AppComponent } from './app.component';
+
+describe('AppComponent', () => {
+  beforeEach(async () => {
+    await TestBed.configureTestingModule({
+      declarations: [
+        AppComponent
+      ],
+    }).compileComponents();
+  });
+
+  it('should create the app', () => {
+    const fixture = TestBed.createComponent(AppComponent);
+    const app = fixture.componentInstance;
+    expect(app).toBeTruthy();
+  });
+
+  it(`should have as title 'angular-todomvc'`, () => {
+    const fixture = TestBed.createComponent(AppComponent);
+    const app = fixture.componentInstance;
+    expect(app.title).toEqual('angular-todomvc');
+  });
+
+  it('should render title', () => {
+    const fixture = TestBed.createComponent(AppComponent);
+    fixture.detectChanges();
+    const compiled = fixture.nativeElement;
+    expect(compiled.querySelector('.content span').textContent).toContain('angular-todomvc app is running!');
+  });
+});

examples/angular-todomvc/src/app/app.component.ts

@@ -0,0 +1,59 @@
+import { Component } from '@angular/core';
+import { RemoteTodoStore, Todo } from './store';
+
+@Component({
+  selector: 'app-root',
+  templateUrl: './app.component.html',
+  styleUrls: ['./app.component.css']
+})
+export class AppComponent {
+  todoStore: RemoteTodoStore;
+  newTodoText = '';
+
+  constructor(todoStore: RemoteTodoStore) {
+    this.todoStore = todoStore;
+  }
+
+  stopEditing(todo: Todo, editedTitle: string) {
+    todo.title = editedTitle;
+    todo.editing = false;
+  }
+
+  cancelEditingTodo(todo: Todo) {
+    todo.editing = false;
+  }
+
+  updateEditingTodo(todo: Todo, editedTitle: string) {
+    editedTitle = editedTitle.trim();
+    todo.editing = false;
+
+    if (editedTitle.length === 0) {
+      return this.todoStore.remove(todo);
+    }
+
+    todo.title = editedTitle;
+  }
+
+  editTodo(todo: Todo) {
+    todo.editing = true;
+  }
+
+  removeCompleted() {
+    this.todoStore.removeCompleted();
+  }
+
+  toggleCompletion(todo: Todo) {
+    this.todoStore.toggleCompletion(todo);
+  }
+
+  remove(todo: Todo){
+    this.todoStore.remove(todo);
+  }
+
+  addTodo() {
+    if (this.newTodoText.trim().length) {
+      this.todoStore.add(this.newTodoText);
+      this.newTodoText = '';
+    }
+  }
+}

examples/angular-todomvc/src/app/app.module.ts

@@ -0,0 +1,19 @@
+import { BrowserModule } from '@angular/platform-browser';
+import { NgModule } from '@angular/core';
+
+import { AppComponent } from './app.component';
+import { RemoteTodoStore } from './store';
+import { FormsModule } from "@angular/forms";
+
+@NgModule({
+  declarations: [
+    AppComponent
+  ],
+  imports: [
+    BrowserModule,
+    FormsModule
+  ],
+  providers: [RemoteTodoStore],
+  bootstrap: [AppComponent]
+})
+export class AppModule { }

examples/angular-todomvc/src/app/store.ts

@@ -0,0 +1,95 @@
+import { io, Socket } from "socket.io-client";
+
+export class Todo {
+  completed: boolean;
+  editing: boolean;
+
+  private _title: String = "";
+  get title() {
+    return this._title;
+  }
+  set title(value: String) {
+    this._title = value.trim();
+  }
+
+  constructor(title: String) {
+    this.completed = false;
+    this.editing = false;
+    this.title = title.trim();
+  }
+}
+
+export class TodoStore {
+  todos: Array<Todo>;
+
+  constructor() {
+    let persistedTodos = JSON.parse(localStorage.getItem('angular2-todos') || '[]');
+    // Normalize back into classes
+    this.todos = persistedTodos.map( (todo: {_title: String, completed: boolean}) => {
+      let ret = new Todo(todo._title);
+      ret.completed = todo.completed;
+      return ret;
+    });
+  }
+
+  protected updateStore() {
+    localStorage.setItem('angular2-todos', JSON.stringify(this.todos));
+  }
+
+  private getWithCompleted(completed: boolean) {
+    return this.todos.filter((todo: Todo) => todo.completed === completed);
+  }
+
+  allCompleted() {
+    return this.todos.length === this.getCompleted().length;
+  }
+
+  setAllTo(completed: boolean) {
+    this.todos.forEach((t: Todo) => t.completed = completed);
+    this.updateStore();
+  }
+
+  removeCompleted() {
+    this.todos = this.getWithCompleted(false);
+    this.updateStore();
+  }
+
+  getRemaining() {
+    return this.getWithCompleted(false);
+  }
+
+  getCompleted() {
+    return this.getWithCompleted(true);
+  }
+
+  toggleCompletion(todo: Todo) {
+    todo.completed = !todo.completed;
+    this.updateStore();
+  }
+
+  remove(todo: Todo) {
+    this.todos.splice(this.todos.indexOf(todo), 1);
+    this.updateStore();
+  }
+
+  add(title: String) {
+    this.todos.push(new Todo(title));
+    this.updateStore();
+  }
+}
+
+export class RemoteTodoStore extends TodoStore {
+  private socket: Socket;
+
+  constructor() {
+    super();
+    this.socket = io("http://localhost:8080");
+    this.socket.on("todos", (updatedTodos: Array<Todo>) => {
+      this.todos = updatedTodos;
+    });
+  }
+
+  protected updateStore() {
+    this.socket.emit("update-store", this.todos.map(({ title, editing, completed }) => ({ title, editing, completed })));
+  }
+}

examples/angular-todomvc/src/environments/environment.prod.ts

@@ -0,0 +1,3 @@
+export const environment = {
+  production: true
+};

examples/angular-todomvc/src/environments/environment.ts

@@ -0,0 +1,16 @@
+// This file can be replaced during build by using the `fileReplacements` array.
+// `ng build --prod` replaces `environment.ts` with `environment.prod.ts`.
+// The list of file replacements can be found in `angular.json`.
+
+export const environment = {
+  production: false
+};
+
+/*
+ * For easier debugging in development mode, you can import the following file
+ * to ignore zone related error stack frames such as `zone.run`, `zoneDelegate.invokeTask`.
+ *
+ * This import should be commented out in production mode because it will have a negative impact
+ * on performance if an error is thrown.
+ */
+// import 'zone.js/dist/zone-error';  // Included with Angular CLI.

examples/angular-todomvc/src/index.html

@@ -0,0 +1,13 @@
+<!doctype html>
+<html lang="en">
+<head>
+  <meta charset="utf-8">
+  <title>Angular Todo MVC</title>
+  <base href="/">
+  <meta name="viewport" content="width=device-width, initial-scale=1">
+  <link rel="icon" type="image/x-icon" href="favicon.ico">
+</head>
+<body>
+  <app-root></app-root>
+</body>
+</html>

examples/angular-todomvc/src/main.ts

@@ -0,0 +1,12 @@
+import { enableProdMode } from '@angular/core';
+import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
+
+import { AppModule } from './app/app.module';
+import { environment } from './environments/environment';
+
+if (environment.production) {
+  enableProdMode();
+}
+
+platformBrowserDynamic().bootstrapModule(AppModule)
+  .catch(err => console.error(err));

examples/angular-todomvc/src/polyfills.ts

@@ -0,0 +1,63 @@
+/**
+ * This file includes polyfills needed by Angular and is loaded before the app.
+ * You can add your own extra polyfills to this file.
+ *
+ * This file is divided into 2 sections:
+ *   1. Browser polyfills. These are applied before loading ZoneJS and are sorted by browsers.
+ *   2. Application imports. Files imported after ZoneJS that should be loaded before your main
+ *      file.
+ *
+ * The current setup is for so-called "evergreen" browsers; the last versions of browsers that
+ * automatically update themselves. This includes Safari >= 10, Chrome >= 55 (including Opera),
+ * Edge >= 13 on the desktop, and iOS 10 and Chrome on mobile.
+ *
+ * Learn more in https://angular.io/guide/browser-support
+ */
+
+/***************************************************************************************************
+ * BROWSER POLYFILLS
+ */
+
+/** IE11 requires the following for NgClass support on SVG elements */
+// import 'classlist.js';  // Run `npm install --save classlist.js`.
+
+/**
+ * Web Animations `@angular/platform-browser/animations`
+ * Only required if AnimationBuilder is used within the application and using IE/Edge or Safari.
+ * Standard animation support in Angular DOES NOT require any polyfills (as of Angular 6.0).
+ */
+// import 'web-animations-js';  // Run `npm install --save web-animations-js`.
+
+/**
+ * By default, zone.js will patch all possible macroTask and DomEvents
+ * user can disable parts of macroTask/DomEvents patch by setting following flags
+ * because those flags need to be set before `zone.js` being loaded, and webpack
+ * will put import in the top of bundle, so user need to create a separate file
+ * in this directory (for example: zone-flags.ts), and put the following flags
+ * into that file, and then add the following code before importing zone.js.
+ * import './zone-flags';
+ *
+ * The flags allowed in zone-flags.ts are listed here.
+ *
+ * The following flags will work for all browsers.
+ *
+ * (window as any).__Zone_disable_requestAnimationFrame = true; // disable patch requestAnimationFrame
+ * (window as any).__Zone_disable_on_property = true; // disable patch onProperty such as onclick
+ * (window as any).__zone_symbol__UNPATCHED_EVENTS = ['scroll', 'mousemove']; // disable patch specified eventNames
+ *
+ *  in IE/Edge developer tools, the addEventListener will also be wrapped by zone.js
+ *  with the following flag, it will bypass `zone.js` patch for IE/Edge
+ *
+ *  (window as any).__Zone_enable_cross_context_check = true;
+ *
+ */
+
+/***************************************************************************************************
+ * Zone JS is required by default for Angular itself.
+ */
+import 'zone.js/dist/zone';  // Included with Angular CLI.
+
+
+/***************************************************************************************************
+ * APPLICATION IMPORTS
+ */

examples/angular-todomvc/src/styles.css

@@ -0,0 +1,381 @@
+/* imported from node_modules/todomvc-app-css/index.css */
+html,
+body {
+  margin: 0;
+  padding: 0;
+}
+
+button {
+  margin: 0;
+  padding: 0;
+  border: 0;
+  background: none;
+  font-size: 100%;
+  vertical-align: baseline;
+  font-family: inherit;
+  font-weight: inherit;
+  color: inherit;
+  -webkit-appearance: none;
+  appearance: none;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
+body {
+  font: 14px 'Helvetica Neue', Helvetica, Arial, sans-serif;
+  line-height: 1.4em;
+  background: #f5f5f5;
+  color: #111111;
+  min-width: 230px;
+  max-width: 550px;
+  margin: 0 auto;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+  font-weight: 300;
+}
+
+:focus {
+  outline: 0;
+}
+
+.hidden {
+  display: none;
+}
+
+.todoapp {
+  background: #fff;
+  margin: 130px 0 40px 0;
+  position: relative;
+  box-shadow: 0 2px 4px 0 rgba(0, 0, 0, 0.2),
+  0 25px 50px 0 rgba(0, 0, 0, 0.1);
+}
+
+.todoapp input::-webkit-input-placeholder {
+  font-style: italic;
+  font-weight: 300;
+  color: rgba(0, 0, 0, 0.4);
+}
+
+.todoapp input::-moz-placeholder {
+  font-style: italic;
+  font-weight: 300;
+  color: rgba(0, 0, 0, 0.4);
+}
+
+.todoapp input::input-placeholder {
+  font-style: italic;
+  font-weight: 300;
+  color: rgba(0, 0, 0, 0.4);
+}
+
+.todoapp h1 {
+  position: absolute;
+  top: -140px;
+  width: 100%;
+  font-size: 80px;
+  font-weight: 200;
+  text-align: center;
+  color: #b83f45;
+  -webkit-text-rendering: optimizeLegibility;
+  -moz-text-rendering: optimizeLegibility;
+  text-rendering: optimizeLegibility;
+}
+
+.new-todo,
+.edit {
+  position: relative;
+  margin: 0;
+  width: 100%;
+  font-size: 24px;
+  font-family: inherit;
+  font-weight: inherit;
+  line-height: 1.4em;
+  color: inherit;
+  padding: 6px;
+  border: 1px solid #999;
+  box-shadow: inset 0 -1px 5px 0 rgba(0, 0, 0, 0.2);
+  box-sizing: border-box;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
+.new-todo {
+  padding: 16px 16px 16px 60px;
+  border: none;
+  background: rgba(0, 0, 0, 0.003);
+  box-shadow: inset 0 -2px 1px rgba(0,0,0,0.03);
+}
+
+.main {
+  position: relative;
+  z-index: 2;
+  border-top: 1px solid #e6e6e6;
+}
+
+.toggle-all {
+  width: 1px;
+  height: 1px;
+  border: none; /* Mobile Safari */
+  opacity: 0;
+  position: absolute;
+  right: 100%;
+  bottom: 100%;
+}
+
+.toggle-all + label {
+  width: 60px;
+  height: 34px;
+  font-size: 0;
+  position: absolute;
+  top: -52px;
+  left: -13px;
+  -webkit-transform: rotate(90deg);
+  transform: rotate(90deg);
+}
+
+.toggle-all + label:before {
+  content: '❯';
+  font-size: 22px;
+  color: #e6e6e6;
+  padding: 10px 27px 10px 27px;
+}
+
+.toggle-all:checked + label:before {
+  color: #737373;
+}
+
+.todo-list {
+  margin: 0;
+  padding: 0;
+  list-style: none;
+}
+
+.todo-list li {
+  position: relative;
+  font-size: 24px;
+  border-bottom: 1px solid #ededed;
+}
+
+.todo-list li:last-child {
+  border-bottom: none;
+}
+
+.todo-list li.editing {
+  border-bottom: none;
+  padding: 0;
+}
+
+.todo-list li.editing .edit {
+  display: block;
+  width: calc(100% - 43px);
+  padding: 12px 16px;
+  margin: 0 0 0 43px;
+}
+
+.todo-list li.editing .view {
+  display: none;
+}
+
+.todo-list li .toggle {
+  text-align: center;
+  width: 40px;
+  /* auto, since non-WebKit browsers doesn't support input styling */
+  height: auto;
+  position: absolute;
+  top: 0;
+  bottom: 0;
+  margin: auto 0;
+  border: none; /* Mobile Safari */
+  -webkit-appearance: none;
+  appearance: none;
+}
+
+.todo-list li .toggle {
+  opacity: 0;
+}
+
+.todo-list li .toggle + label {
+  /*
+    Firefox requires `#` to be escaped - https://bugzilla.mozilla.org/show_bug.cgi?id=922433
+    IE and Edge requires *everything* to be escaped to render, so we do that instead of just the `#` - https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/7157459/
+  */
+  background-image: url('data:image/svg+xml;utf8,%3Csvg%20xmlns%3D%22http%3A//www.w3.org/2000/svg%22%20width%3D%2240%22%20height%3D%2240%22%20viewBox%3D%22-10%20-18%20100%20135%22%3E%3Ccircle%20cx%3D%2250%22%20cy%3D%2250%22%20r%3D%2250%22%20fill%3D%22none%22%20stroke%3D%22%23ededed%22%20stroke-width%3D%223%22/%3E%3C/svg%3E');
+  background-repeat: no-repeat;
+  background-position: center left;
+}
+
+.todo-list li .toggle:checked + label {
+  background-image: url('data:image/svg+xml;utf8,%3Csvg%20xmlns%3D%22http%3A//www.w3.org/2000/svg%22%20width%3D%2240%22%20height%3D%2240%22%20viewBox%3D%22-10%20-18%20100%20135%22%3E%3Ccircle%20cx%3D%2250%22%20cy%3D%2250%22%20r%3D%2250%22%20fill%3D%22none%22%20stroke%3D%22%23bddad5%22%20stroke-width%3D%223%22/%3E%3Cpath%20fill%3D%22%235dc2af%22%20d%3D%22M72%2025L42%2071%2027%2056l-4%204%2020%2020%2034-52z%22/%3E%3C/svg%3E');
+}
+
+.todo-list li label {
+  word-break: break-all;
+  padding: 15px 15px 15px 60px;
+  display: block;
+  line-height: 1.2;
+  transition: color 0.4s;
+  font-weight: 400;
+  color: #4d4d4d;
+}
+
+.todo-list li.completed label {
+  color: #cdcdcd;
+  text-decoration: line-through;
+}
+
+.todo-list li .destroy {
+  display: none;
+  position: absolute;
+  top: 0;
+  right: 10px;
+  bottom: 0;
+  width: 40px;
+  height: 40px;
+  margin: auto 0;
+  font-size: 30px;
+  color: #cc9a9a;
+  margin-bottom: 11px;
+  transition: color 0.2s ease-out;
+}
+
+.todo-list li .destroy:hover {
+  color: #af5b5e;
+}
+
+.todo-list li .destroy:after {
+  content: '×';
+}
+
+.todo-list li:hover .destroy {
+  display: block;
+}
+
+.todo-list li .edit {
+  display: none;
+}
+
+.todo-list li.editing:last-child {
+  margin-bottom: -1px;
+}
+
+.footer {
+  padding: 10px 15px;
+  height: 20px;
+  text-align: center;
+  font-size: 15px;
+  border-top: 1px solid #e6e6e6;
+}
+
+.footer:before {
+  content: '';
+  position: absolute;
+  right: 0;
+  bottom: 0;
+  left: 0;
+  height: 50px;
+  overflow: hidden;
+  box-shadow: 0 1px 1px rgba(0, 0, 0, 0.2),
+  0 8px 0 -3px #f6f6f6,
+  0 9px 1px -3px rgba(0, 0, 0, 0.2),
+  0 16px 0 -6px #f6f6f6,
+  0 17px 2px -6px rgba(0, 0, 0, 0.2);
+}
+
+.todo-count {
+  float: left;
+  text-align: left;
+}
+
+.todo-count strong {
+  font-weight: 300;
+}
+
+.filters {
+  margin: 0;
+  padding: 0;
+  list-style: none;
+  position: absolute;
+  right: 0;
+  left: 0;
+}
+
+.filters li {
+  display: inline;
+}
+
+.filters li a {
+  color: inherit;
+  margin: 3px;
+  padding: 3px 7px;
+  text-decoration: none;
+  border: 1px solid transparent;
+  border-radius: 3px;
+}
+
+.filters li a:hover {
+  border-color: rgba(175, 47, 47, 0.1);
+}
+
+.filters li a.selected {
+  border-color: rgba(175, 47, 47, 0.2);
+}
+
+.clear-completed,
+html .clear-completed:active {
+  float: right;
+  position: relative;
+  line-height: 20px;
+  text-decoration: none;
+  cursor: pointer;
+}
+
+.clear-completed:hover {
+  text-decoration: underline;
+}
+
+.info {
+  margin: 65px auto 0;
+  color: #4d4d4d;
+  font-size: 11px;
+  text-shadow: 0 1px 0 rgba(255, 255, 255, 0.5);
+  text-align: center;
+}
+
+.info p {
+  line-height: 1;
+}
+
+.info a {
+  color: inherit;
+  text-decoration: none;
+  font-weight: 400;
+}
+
+.info a:hover {
+  text-decoration: underline;
+}
+
+/*
+	Hack to remove background from Mobile Safari.
+	Can't use it globally since it destroys checkboxes in Firefox
+*/
+@media screen and (-webkit-min-device-pixel-ratio:0) {
+  .toggle-all,
+  .todo-list li .toggle {
+    background: none;
+  }
+
+  .todo-list li .toggle {
+    height: 40px;
+  }
+}
+
+@media (max-width: 430px) {
+  .footer {
+    height: 50px;
+  }
+
+  .filters {
+    bottom: 10px;
+  }
+}

examples/angular-todomvc/src/test.ts

@@ -0,0 +1,25 @@
+// This file is required by karma.conf.js and loads recursively all the .spec and framework files
+
+import 'zone.js/dist/zone-testing';
+import { getTestBed } from '@angular/core/testing';
+import {
+  BrowserDynamicTestingModule,
+  platformBrowserDynamicTesting
+} from '@angular/platform-browser-dynamic/testing';
+
+declare const require: {
+  context(path: string, deep?: boolean, filter?: RegExp): {
+    keys(): string[];
+    <T>(id: string): T;
+  };
+};
+
+// First, initialize the Angular testing environment.
+getTestBed().initTestEnvironment(
+  BrowserDynamicTestingModule,
+  platformBrowserDynamicTesting()
+);
+// Then we find all the tests.
+const context = require.context('./', true, /\.spec\.ts$/);
+// And load the modules.
+context.keys().map(context);

examples/angular-todomvc/tsconfig.app.json

@@ -0,0 +1,15 @@
+/* To learn more about this file see: https://angular.io/config/tsconfig. */
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "outDir": "./out-tsc/app",
+    "types": []
+  },
+  "files": [
+    "src/main.ts",
+    "src/polyfills.ts"
+  ],
+  "include": [
+    "src/**/*.d.ts"
+  ]
+}

examples/angular-todomvc/tsconfig.json

@@ -0,0 +1,29 @@
+/* To learn more about this file see: https://angular.io/config/tsconfig. */
+{
+  "compileOnSave": false,
+  "compilerOptions": {
+    "baseUrl": "./",
+    "outDir": "./dist/out-tsc",
+    "forceConsistentCasingInFileNames": true,
+    "strict": true,
+    "noImplicitReturns": true,
+    "noFallthroughCasesInSwitch": true,
+    "sourceMap": true,
+    "declaration": false,
+    "downlevelIteration": true,
+    "experimentalDecorators": true,
+    "moduleResolution": "node",
+    "importHelpers": true,
+    "target": "es2015",
+    "module": "es2020",
+    "lib": [
+      "es2018",
+      "dom"
+    ]
+  },
+  "angularCompilerOptions": {
+    "strictInjectionParameters": true,
+    "strictInputAccessModifiers": true,
+    "strictTemplates": true
+  }
+}

examples/angular-todomvc/tsconfig.spec.json

@@ -0,0 +1,18 @@
+/* To learn more about this file see: https://angular.io/config/tsconfig. */
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "outDir": "./out-tsc/spec",
+    "types": [
+      "jasmine"
+    ]
+  },
+  "files": [
+    "src/test.ts",
+    "src/polyfills.ts"
+  ],
+  "include": [
+    "src/**/*.spec.ts",
+    "src/**/*.d.ts"
+  ]
+}

examples/angular-todomvc/tslint.json

@@ -0,0 +1,152 @@
+{
+  "extends": "tslint:recommended",
+  "rulesDirectory": [
+    "codelyzer"
+  ],
+  "rules": {
+    "align": {
+      "options": [
+        "parameters",
+        "statements"
+      ]
+    },
+    "array-type": false,
+    "arrow-return-shorthand": true,
+    "curly": true,
+    "deprecation": {
+      "severity": "warning"
+    },
+    "eofline": true,
+    "import-blacklist": [
+      true,
+      "rxjs/Rx"
+    ],
+    "import-spacing": true,
+    "indent": {
+      "options": [
+        "spaces"
+      ]
+    },
+    "max-classes-per-file": false,
+    "max-line-length": [
+      true,
+      140
+    ],
+    "member-ordering": [
+      true,
+      {
+        "order": [
+          "static-field",
+          "instance-field",
+          "static-method",
+          "instance-method"
+        ]
+      }
+    ],
+    "no-console": [
+      true,
+      "debug",
+      "info",
+      "time",
+      "timeEnd",
+      "trace"
+    ],
+    "no-empty": false,
+    "no-inferrable-types": [
+      true,
+      "ignore-params"
+    ],
+    "no-non-null-assertion": true,
+    "no-redundant-jsdoc": true,
+    "no-switch-case-fall-through": true,
+    "no-var-requires": false,
+    "object-literal-key-quotes": [
+      true,
+      "as-needed"
+    ],
+    "quotemark": [
+      true,
+      "single"
+    ],
+    "semicolon": {
+      "options": [
+        "always"
+      ]
+    },
+    "space-before-function-paren": {
+      "options": {
+        "anonymous": "never",
+        "asyncArrow": "always",
+        "constructor": "never",
+        "method": "never",
+        "named": "never"
+      }
+    },
+    "typedef": [
+      true,
+      "call-signature"
+    ],
+    "typedef-whitespace": {
+      "options": [
+        {
+          "call-signature": "nospace",
+          "index-signature": "nospace",
+          "parameter": "nospace",
+          "property-declaration": "nospace",
+          "variable-declaration": "nospace"
+        },
+        {
+          "call-signature": "onespace",
+          "index-signature": "onespace",
+          "parameter": "onespace",
+          "property-declaration": "onespace",
+          "variable-declaration": "onespace"
+        }
+      ]
+    },
+    "variable-name": {
+      "options": [
+        "ban-keywords",
+        "check-format",
+        "allow-pascal-case"
+      ]
+    },
+    "whitespace": {
+      "options": [
+        "check-branch",
+        "check-decl",
+        "check-operator",
+        "check-separator",
+        "check-type",
+        "check-typecast"
+      ]
+    },
+    "component-class-suffix": true,
+    "contextual-lifecycle": true,
+    "directive-class-suffix": true,
+    "no-conflicting-lifecycle": true,
+    "no-host-metadata-property": true,
+    "no-input-rename": true,
+    "no-inputs-metadata-property": true,
+    "no-output-native": true,
+    "no-output-on-prefix": true,
+    "no-output-rename": true,
+    "no-outputs-metadata-property": true,
+    "template-banana-in-box": true,
+    "template-no-negated-async": true,
+    "use-lifecycle-interface": true,
+    "use-pipe-transform-interface": true,
+    "directive-selector": [
+      true,
+      "attribute",
+      "app",
+      "camelCase"
+    ],
+    "component-selector": [
+      true,
+      "element",
+      "app",
+      "kebab-case"
+    ]
+  }
+}

examples/chat/public/main.js

@@ -1,36 +1,36 @@
 $(function() {
-  var FADE_TIME = 150; // ms
-  var TYPING_TIMER_LENGTH = 400; // ms
-  var COLORS = [
+  const FADE_TIME = 150; // ms
+  const TYPING_TIMER_LENGTH = 400; // ms
+  const COLORS = [
     '#e21400', '#91580f', '#f8a700', '#f78b00',
     '#58dc00', '#287b00', '#a8f07a', '#4ae8c4',
     '#3b88eb', '#3824aa', '#a700ff', '#d300e7'
   ];
 
   // Initialize variables
-  var $window = $(window);
-  var $usernameInput = $('.usernameInput'); // Input for username
-  var $messages = $('.messages'); // Messages area
-  var $inputMessage = $('.inputMessage'); // Input message input box
+  const $window = $(window);
+  const $usernameInput = $('.usernameInput'); // Input for username
+  const $messages = $('.messages');           // Messages area
+  const $inputMessage = $('.inputMessage');   // Input message input box
 
-  var $loginPage = $('.login.page'); // The login page
-  var $chatPage = $('.chat.page'); // The chatroom page
+  const $loginPage = $('.login.page');        // The login page
+  const $chatPage = $('.chat.page');          // The chatroom page
+
+  const socket = io();
 
   // Prompt for setting a username
-  var username;
-  var connected = false;
-  var typing = false;
-  var lastTypingTime;
-  var $currentInput = $usernameInput.focus();
-
-  var socket = io();
+  let username;
+  let connected = false;
+  let typing = false;
+  let lastTypingTime;
+  let $currentInput = $usernameInput.focus();
 
   const addParticipantsMessage = (data) => {
-    var message = '';
+    let message = '';
     if (data.numUsers === 1) {
-      message += "there's 1 participant";
+      message += `there's 1 participant`;
     } else {
-      message += "there are " + data.numUsers + " participants";
+      message += `there are ${data.numUsers} participants`;
     }
     log(message);
   }
@@ -53,45 +53,41 @@ $(function() {
 
   // Sends a chat message
   const sendMessage = () => {
-    var message = $inputMessage.val();
+    let message = $inputMessage.val();
     // Prevent markup from being injected into the message
     message = cleanInput(message);
     // if there is a non-empty message and a socket connection
     if (message && connected) {
       $inputMessage.val('');
-      addChatMessage({
-        username: username,
-        message: message
-      });
+      addChatMessage({ username, message });
       // tell server to execute 'new message' and send along one parameter
       socket.emit('new message', message);
     }
   }
 
   // Log a message
-    const log = (message, options) => {
-    var $el = $('<li>').addClass('log').text(message);
+  const log = (message, options) => {
+    const $el = $('<li>').addClass('log').text(message);
     addMessageElement($el, options);
   }
 
   // Adds the visual chat message to the message list
   const addChatMessage = (data, options) => {
     // Don't fade the message in if there is an 'X was typing'
-    var $typingMessages = getTypingMessages(data);
-    options = options || {};
+    const $typingMessages = getTypingMessages(data);
     if ($typingMessages.length !== 0) {
       options.fade = false;
       $typingMessages.remove();
     }
 
-    var $usernameDiv = $('<span class="username"/>')
+    const $usernameDiv = $('<span class="username"/>')
       .text(data.username)
       .css('color', getUsernameColor(data.username));
-    var $messageBodyDiv = $('<span class="messageBody">')
+    const $messageBodyDiv = $('<span class="messageBody">')
       .text(data.message);
 
-    var typingClass = data.typing ? 'typing' : '';
-    var $messageDiv = $('<li class="message"/>')
+    const typingClass = data.typing ? 'typing' : '';
+    const $messageDiv = $('<li class="message"/>')
       .data('username', data.username)
       .addClass(typingClass)
       .append($usernameDiv, $messageBodyDiv);
@@ -119,8 +115,7 @@ $(function() {
   // options.prepend - If the element should prepend
   //   all other messages (default = false)
   const addMessageElement = (el, options) => {
-    var $el = $(el);
-
+    const $el = $(el);
     // Setup default options
     if (!options) {
       options = {};
@@ -141,6 +136,7 @@ $(function() {
     } else {
       $messages.append($el);
     }
+
     $messages[0].scrollTop = $messages[0].scrollHeight;
   }
 
@@ -159,8 +155,8 @@ $(function() {
       lastTypingTime = (new Date()).getTime();
 
       setTimeout(() => {
-        var typingTimer = (new Date()).getTime();
-        var timeDiff = typingTimer - lastTypingTime;
+        const typingTimer = (new Date()).getTime();
+        const timeDiff = typingTimer - lastTypingTime;
         if (timeDiff >= TYPING_TIMER_LENGTH && typing) {
           socket.emit('stop typing');
           typing = false;
@@ -179,12 +175,12 @@ $(function() {
   // Gets the color of a username through our hash function
   const getUsernameColor = (username) => {
     // Compute hash code
-    var hash = 7;
-    for (var i = 0; i < username.length; i++) {
-       hash = username.charCodeAt(i) + (hash << 5) - hash;
+    let hash = 7;
+    for (let i = 0; i < username.length; i++) {
+      hash = username.charCodeAt(i) + (hash << 5) - hash;
     }
     // Calculate color
-    var index = Math.abs(hash % COLORS.length);
+    const index = Math.abs(hash % COLORS.length);
     return COLORS[index];
   }
 
@@ -229,7 +225,7 @@ $(function() {
   socket.on('login', (data) => {
     connected = true;
     // Display the welcome message
-    var message = "Welcome to Socket.IO Chat – ";
+    const message = 'Welcome to Socket.IO Chat – ';
     log(message, {
       prepend: true
     });
@@ -243,13 +239,13 @@ $(function() {
 
   // Whenever the server emits 'user joined', log it in the chat body
   socket.on('user joined', (data) => {
-    log(data.username + ' joined');
+    log(`${data.username} joined`);
     addParticipantsMessage(data);
   });
 
   // Whenever the server emits 'user left', log it in the chat body
   socket.on('user left', (data) => {
-    log(data.username + ' left');
+    log(`${data.username} left`);
     addParticipantsMessage(data);
     removeChatTyping(data);
   });

examples/cluster-haproxy/server/Dockerfile

@@ -1,4 +1,4 @@
-FROM mhart/alpine-node:6
+FROM node:14-alpine
 
 # Create app directory
 RUN mkdir -p /usr/src/app
@@ -6,7 +6,7 @@ WORKDIR /usr/src/app
 
 # Install app dependencies
 COPY package.json /usr/src/app/
-RUN npm install
+RUN npm install --prod
 
 # Bundle app source
 COPY . /usr/src/app

examples/cluster-haproxy/server/package.json

@@ -8,8 +8,8 @@
   "license": "BSD",
   "dependencies": {
     "express": "4.13.4",
-    "socket.io": "^1.7.2",
-    "socket.io-redis": "^3.0.0"
+    "socket.io": "^3.1.0",
+    "socket.io-redis": "^6.0.1"
   },
   "scripts": {
     "start": "node index.js"

examples/cluster-httpd/httpd/httpd.conf

@@ -3,6 +3,8 @@ Listen 80
 
 ServerName localhost
 
+LoadModule mpm_event_module             modules/mod_mpm_event.so
+
 LoadModule authn_file_module            modules/mod_authn_file.so
 LoadModule authn_core_module            modules/mod_authn_core.so
 LoadModule authz_host_module            modules/mod_authz_host.so

examples/cluster-httpd/server/Dockerfile

@@ -6,7 +6,7 @@ WORKDIR /usr/src/app
 
 # Install app dependencies
 COPY package.json /usr/src/app/
-RUN npm install
+RUN npm install --prod
 
 # Bundle app source
 COPY . /usr/src/app

examples/cluster-httpd/server/package.json

@@ -8,8 +8,8 @@
   "license": "BSD",
   "dependencies": {
     "express": "4.13.4",
-    "socket.io": "^1.7.2",
-    "socket.io-redis": "^3.0.0"
+    "socket.io": "^3.1.0",
+    "socket.io-redis": "^6.0.1"
   },
   "scripts": {
     "start": "node index.js"

examples/cluster-nginx/README.md

@@ -22,6 +22,16 @@ Each node connects to the redis backend, which will enable to broadcast to every
 $ docker-compose stop server-george
 ```
 
+A `client` container is included in the `docker-compose.yml` file, in order to test the routing.
+
+You can create additional `client` containers with:
+
+```
+$ docker-compose up -d --scale=client=10 client
+# and then
+$ docker-compose logs client
+```
+
 ## Features
 
 - Multiple users can join a chat room by each entering a unique username

examples/cluster-nginx/client/Dockerfile

@@ -0,0 +1,15 @@
+FROM node:14-alpine
+
+# Create app directory
+RUN mkdir -p /usr/src/app
+WORKDIR /usr/src/app
+
+# Install app dependencies
+COPY package.json /usr/src/app/
+RUN npm install --prod
+
+# Bundle app source
+COPY . /usr/src/app
+
+EXPOSE 3000
+CMD [ "npm", "start" ]

examples/cluster-nginx/client/index.js

@@ -0,0 +1,13 @@
+const socket = require('socket.io-client')('ws://nginx');
+
+socket.on('connect', () => {
+  console.log('connected');
+});
+
+socket.on('my-name-is', (serverName) => {
+  console.log(`connected to ${serverName}`);
+});
+
+socket.on('disconnect', (reason) => {
+  console.log(`disconnected due to ${reason}`);
+});

examples/cluster-nginx/client/package.json

@@ -0,0 +1,15 @@
+{
+  "name": "socket.io-chat",
+  "version": "0.0.0",
+  "description": "A simple chat client using socket.io",
+  "main": "index.js",
+  "author": "Grant Timmerman",
+  "private": true,
+  "license": "MIT",
+  "dependencies": {
+    "socket.io-client": "^3.1.0"
+  },
+  "scripts": {
+    "start": "node index.js"
+  }
+}

examples/cluster-nginx/docker-compose.yml

@@ -45,6 +45,11 @@ server-ringo:
   environment:
     - NAME=Ringo
 
+client:
+  build: ./client
+  links:
+    - nginx
+
 redis:
   image: redis:alpine
   expose:

examples/cluster-nginx/nginx/nginx.conf

@@ -24,8 +24,12 @@ http {
   }
 
   upstream nodes {
-    # enable sticky session
-    ip_hash;
+    # enable sticky session with either "hash" (uses the complete IP address)
+    hash $remote_addr consistent;
+    # or "ip_hash" (uses the first three octets of the client IPv4 address, or the entire IPv6 address)
+    # ip_hash;
+    # or "sticky" (needs commercial subscription)
+    # sticky cookie srv_id expires=1h domain=.example.com path=/;
 
     server server-john:3000;
     server server-paul:3000;

examples/cluster-nginx/server/Dockerfile

@@ -1,4 +1,4 @@
-FROM mhart/alpine-node:6
+FROM node:14-alpine
 
 # Create app directory
 RUN mkdir -p /usr/src/app
@@ -6,7 +6,7 @@ WORKDIR /usr/src/app
 
 # Install app dependencies
 COPY package.json /usr/src/app/
-RUN npm install
+RUN npm install --prod
 
 # Bundle app source
 COPY . /usr/src/app

examples/cluster-nginx/server/package.json

@@ -8,8 +8,8 @@
   "license": "MIT",
   "dependencies": {
     "express": "4.13.4",
-    "socket.io": "^1.7.2",
-    "socket.io-redis": "^3.0.0"
+    "socket.io": "^3.1.0",
+    "socket.io-redis": "^6.0.1"
   },
   "scripts": {
     "start": "node index.js"

examples/cluster-traefik/README.md

@@ -0,0 +1,22 @@
+
+# Socket.IO Chat with traefik & [redis](https://redis.io/)
+
+A simple chat demo for Socket.IO
+
+## How to use
+
+Install [Docker Compose](https://docs.docker.com/compose/install/), then:
+
+```
+$ docker-compose up -d
+```
+
+And then point your browser to `http://localhost:3000`.
+
+You can then scale the server to multiple instances:
+
+```
+$ docker-compose up -d --scale=server=7
+```
+
+The session stickiness, which is [required](https://socket.io/docs/v3/using-multiple-nodes/) when using multiple Socket.IO server instances, is achieved with a cookie. More information [here](https://doc.traefik.io/traefik/v2.0/routing/services/#sticky-sessions).

examples/cluster-traefik/docker-compose.yml

@@ -0,0 +1,27 @@
+version: "3"
+
+services:
+  traefik:
+    image: traefik:2.4
+    volumes:
+      - ./traefik.yml:/etc/traefik/traefik.yml
+      - /var/run/docker.sock:/var/run/docker.sock
+    links:
+      - server
+    ports:
+     - "3000:80"
+     - "8080:8080"
+
+  server:
+    build: ./server
+    links:
+      - redis
+    labels:
+      - "traefik.http.routers.chat.rule=PathPrefix(`/`)"
+      - traefik.http.services.chat.loadBalancer.sticky.cookie.name=server_id
+      - traefik.http.services.chat.loadBalancer.sticky.cookie.httpOnly=true
+
+  redis:
+    image: redis:6-alpine
+    labels:
+      - traefik.enable=false

examples/cluster-traefik/server/Dockerfile

@@ -0,0 +1,15 @@
+FROM node:14-alpine
+
+# Create app directory
+RUN mkdir -p /usr/src/app
+WORKDIR /usr/src/app
+
+# Install app dependencies
+COPY package.json /usr/src/app/
+RUN npm install --prod
+
+# Bundle app source
+COPY . /usr/src/app
+
+EXPOSE 3000
+CMD [ "npm", "start" ]

examples/cluster-traefik/server/index.js

@@ -0,0 +1,83 @@
+// Setup basic express server
+var express = require('express');
+var app = express();
+var server = require('http').createServer(app);
+var io = require('socket.io')(server);
+var redis = require('socket.io-redis');
+var port = process.env.PORT || 3000;
+var crypto = require('crypto');
+var serverName = crypto.randomBytes(3).toString('hex');
+
+io.adapter(redis({ host: 'redis', port: 6379 }));
+
+server.listen(port, function () {
+  console.log('Server listening at port %d', port);
+  console.log('Hello, I\'m %s, how can I help?', serverName);
+});
+
+// Routing
+app.use(express.static(__dirname + '/public'));
+
+// Chatroom
+
+var numUsers = 0;
+
+io.on('connection', function (socket) {
+  socket.emit('my-name-is', serverName);
+
+  var addedUser = false;
+
+  // when the client emits 'new message', this listens and executes
+  socket.on('new message', function (data) {
+    // we tell the client to execute 'new message'
+    socket.broadcast.emit('new message', {
+      username: socket.username,
+      message: data
+    });
+  });
+
+  // when the client emits 'add user', this listens and executes
+  socket.on('add user', function (username) {
+    if (addedUser) return;
+
+    // we store the username in the socket session for this client
+    socket.username = username;
+    ++numUsers;
+    addedUser = true;
+    socket.emit('login', {
+      numUsers: numUsers
+    });
+    // echo globally (all clients) that a person has connected
+    socket.broadcast.emit('user joined', {
+      username: socket.username,
+      numUsers: numUsers
+    });
+  });
+
+  // when the client emits 'typing', we broadcast it to others
+  socket.on('typing', function () {
+    socket.broadcast.emit('typing', {
+      username: socket.username
+    });
+  });
+
+  // when the client emits 'stop typing', we broadcast it to others
+  socket.on('stop typing', function () {
+    socket.broadcast.emit('stop typing', {
+      username: socket.username
+    });
+  });
+
+  // when the user disconnects.. perform this
+  socket.on('disconnect', function () {
+    if (addedUser) {
+      --numUsers;
+
+      // echo globally that this client has left
+      socket.broadcast.emit('user left', {
+        username: socket.username,
+        numUsers: numUsers
+      });
+    }
+  });
+});

examples/cluster-traefik/server/package.json

@@ -0,0 +1,17 @@
+{
+  "name": "socket.io-chat",
+  "version": "0.0.0",
+  "description": "A simple chat client using socket.io",
+  "main": "index.js",
+  "author": "Grant Timmerman",
+  "private": true,
+  "license": "MIT",
+  "dependencies": {
+    "express": "4.13.4",
+    "socket.io": "^3.1.0",
+    "socket.io-redis": "^6.0.1"
+  },
+  "scripts": {
+    "start": "node index.js"
+  }
+}

examples/cluster-traefik/server/public/index.html

@@ -0,0 +1,28 @@
+<!doctype html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <title>Socket.IO Chat Example</title>
+  <link rel="stylesheet" href="style.css">
+</head>
+<body>
+  <ul class="pages">
+    <li class="chat page">
+      <div class="chatArea">
+        <ul class="messages"></ul>
+      </div>
+      <input class="inputMessage" placeholder="Type here..."/>
+    </li>
+    <li class="login page">
+      <div class="form">
+        <h3 class="title">What's your nickname?</h3>
+        <input class="usernameInput" type="text" maxlength="14" />
+      </div>
+    </li>
+  </ul>
+
+  <script src="https://code.jquery.com/jquery-1.10.2.min.js"></script>
+  <script src="/socket.io/socket.io.js"></script>
+  <script src="/main.js"></script>
+</body>
+</html>

examples/cluster-traefik/server/public/main.js

@@ -0,0 +1,286 @@
+$(function() {
+  var FADE_TIME = 150; // ms
+  var TYPING_TIMER_LENGTH = 400; // ms
+  var COLORS = [
+    '#e21400', '#91580f', '#f8a700', '#f78b00',
+    '#58dc00', '#287b00', '#a8f07a', '#4ae8c4',
+    '#3b88eb', '#3824aa', '#a700ff', '#d300e7'
+  ];
+
+  // Initialize variables
+  var $window = $(window);
+  var $usernameInput = $('.usernameInput'); // Input for username
+  var $messages = $('.messages'); // Messages area
+  var $inputMessage = $('.inputMessage'); // Input message input box
+
+  var $loginPage = $('.login.page'); // The login page
+  var $chatPage = $('.chat.page'); // The chatroom page
+
+  // Prompt for setting a username
+  var username;
+  var connected = false;
+  var typing = false;
+  var lastTypingTime;
+  var $currentInput = $usernameInput.focus();
+
+  var socket = io();
+
+  function addParticipantsMessage (data) {
+    var message = '';
+    if (data.numUsers === 1) {
+      message += "there's 1 participant";
+    } else {
+      message += "there are " + data.numUsers + " participants";
+    }
+    log(message);
+  }
+
+  // Sets the client's username
+  function setUsername () {
+    username = cleanInput($usernameInput.val().trim());
+
+    // If the username is valid
+    if (username) {
+      $loginPage.fadeOut();
+      $chatPage.show();
+      $loginPage.off('click');
+      $currentInput = $inputMessage.focus();
+
+      // Tell the server your username
+      socket.emit('add user', username);
+    }
+  }
+
+  // Sends a chat message
+  function sendMessage () {
+    var message = $inputMessage.val();
+    // Prevent markup from being injected into the message
+    message = cleanInput(message);
+    // if there is a non-empty message and a socket connection
+    if (message && connected) {
+      $inputMessage.val('');
+      addChatMessage({
+        username: username,
+        message: message
+      });
+      // tell server to execute 'new message' and send along one parameter
+      socket.emit('new message', message);
+    }
+  }
+
+  // Log a message
+  function log (message, options) {
+    var $el = $('<li>').addClass('log').text(message);
+    addMessageElement($el, options);
+  }
+
+  // Adds the visual chat message to the message list
+  function addChatMessage (data, options) {
+    // Don't fade the message in if there is an 'X was typing'
+    var $typingMessages = getTypingMessages(data);
+    options = options || {};
+    if ($typingMessages.length !== 0) {
+      options.fade = false;
+      $typingMessages.remove();
+    }
+
+    var $usernameDiv = $('<span class="username"/>')
+      .text(data.username)
+      .css('color', getUsernameColor(data.username));
+    var $messageBodyDiv = $('<span class="messageBody">')
+      .text(data.message);
+
+    var typingClass = data.typing ? 'typing' : '';
+    var $messageDiv = $('<li class="message"/>')
+      .data('username', data.username)
+      .addClass(typingClass)
+      .append($usernameDiv, $messageBodyDiv);
+
+    addMessageElement($messageDiv, options);
+  }
+
+  // Adds the visual chat typing message
+  function addChatTyping (data) {
+    data.typing = true;
+    data.message = 'is typing';
+    addChatMessage(data);
+  }
+
+  // Removes the visual chat typing message
+  function removeChatTyping (data) {
+    getTypingMessages(data).fadeOut(function () {
+      $(this).remove();
+    });
+  }
+
+  // Adds a message element to the messages and scrolls to the bottom
+  // el - The element to add as a message
+  // options.fade - If the element should fade-in (default = true)
+  // options.prepend - If the element should prepend
+  //   all other messages (default = false)
+  function addMessageElement (el, options) {
+    var $el = $(el);
+
+    // Setup default options
+    if (!options) {
+      options = {};
+    }
+    if (typeof options.fade === 'undefined') {
+      options.fade = true;
+    }
+    if (typeof options.prepend === 'undefined') {
+      options.prepend = false;
+    }
+
+    // Apply options
+    if (options.fade) {
+      $el.hide().fadeIn(FADE_TIME);
+    }
+    if (options.prepend) {
+      $messages.prepend($el);
+    } else {
+      $messages.append($el);
+    }
+    $messages[0].scrollTop = $messages[0].scrollHeight;
+  }
+
+  // Prevents input from having injected markup
+  function cleanInput (input) {
+    return $('<div/>').text(input).text();
+  }
+
+  // Updates the typing event
+  function updateTyping () {
+    if (connected) {
+      if (!typing) {
+        typing = true;
+        socket.emit('typing');
+      }
+      lastTypingTime = (new Date()).getTime();
+
+      setTimeout(function () {
+        var typingTimer = (new Date()).getTime();
+        var timeDiff = typingTimer - lastTypingTime;
+        if (timeDiff >= TYPING_TIMER_LENGTH && typing) {
+          socket.emit('stop typing');
+          typing = false;
+        }
+      }, TYPING_TIMER_LENGTH);
+    }
+  }
+
+  // Gets the 'X is typing' messages of a user
+  function getTypingMessages (data) {
+    return $('.typing.message').filter(function (i) {
+      return $(this).data('username') === data.username;
+    });
+  }
+
+  // Gets the color of a username through our hash function
+  function getUsernameColor (username) {
+    // Compute hash code
+    var hash = 7;
+    for (var i = 0; i < username.length; i++) {
+       hash = username.charCodeAt(i) + (hash << 5) - hash;
+    }
+    // Calculate color
+    var index = Math.abs(hash % COLORS.length);
+    return COLORS[index];
+  }
+
+  // Keyboard events
+
+  $window.keydown(function (event) {
+    // Auto-focus the current input when a key is typed
+    if (!(event.ctrlKey || event.metaKey || event.altKey)) {
+      $currentInput.focus();
+    }
+    // When the client hits ENTER on their keyboard
+    if (event.which === 13) {
+      if (username) {
+        sendMessage();
+        socket.emit('stop typing');
+        typing = false;
+      } else {
+        setUsername();
+      }
+    }
+  });
+
+  $inputMessage.on('input', function() {
+    updateTyping();
+  });
+
+  // Click events
+
+  // Focus input when clicking anywhere on login page
+  $loginPage.click(function () {
+    $currentInput.focus();
+  });
+
+  // Focus input when clicking on the message input's border
+  $inputMessage.click(function () {
+    $inputMessage.focus();
+  });
+
+  // Socket events
+
+  // Whenever the server emits 'login', log the login message
+  socket.on('login', function (data) {
+    connected = true;
+    // Display the welcome message
+    var message = "Welcome to Socket.IO Chat – ";
+    log(message, {
+      prepend: true
+    });
+    addParticipantsMessage(data);
+  });
+
+  // Whenever the server emits 'new message', update the chat body
+  socket.on('new message', function (data) {
+    addChatMessage(data);
+  });
+
+  // Whenever the server emits 'user joined', log it in the chat body
+  socket.on('user joined', function (data) {
+    log(data.username + ' joined');
+    addParticipantsMessage(data);
+  });
+
+  // Whenever the server emits 'user left', log it in the chat body
+  socket.on('user left', function (data) {
+    log(data.username + ' left');
+    addParticipantsMessage(data);
+    removeChatTyping(data);
+  });
+
+  // Whenever the server emits 'typing', show the typing message
+  socket.on('typing', function (data) {
+    addChatTyping(data);
+  });
+
+  // Whenever the server emits 'stop typing', kill the typing message
+  socket.on('stop typing', function (data) {
+    removeChatTyping(data);
+  });
+
+  socket.on('disconnect', function () {
+    log('you have been disconnected');
+  });
+
+  socket.on('connect', function () {
+    if (username) {
+      log('you have been reconnected');
+      socket.emit('add user', username);
+    }
+  });
+
+  socket.io.on('reconnect_error', function () {
+    log('attempt to reconnect has failed');
+  });
+
+  socket.on('my-name-is', function (serverName) {
+    log('host is now ' + serverName);
+  })
+
+});

examples/cluster-traefik/server/public/style.css

@@ -0,0 +1,149 @@
+/* Fix user-agent */
+
+* {
+  box-sizing: border-box;
+}
+
+html {
+  font-weight: 300;
+  -webkit-font-smoothing: antialiased;
+}
+
+html, input {
+  font-family:
+    "HelveticaNeue-Light",
+    "Helvetica Neue Light",
+    "Helvetica Neue",
+    Helvetica,
+    Arial,
+    "Lucida Grande",
+    sans-serif;
+}
+
+html, body {
+  height: 100%;
+  margin: 0;
+  padding: 0;
+}
+
+ul {
+  list-style: none;
+  word-wrap: break-word;
+}
+
+/* Pages */
+
+.pages {
+  height: 100%;
+  margin: 0;
+  padding: 0;
+  width: 100%;
+}
+
+.page {
+  height: 100%;
+  position: absolute;
+  width: 100%;
+}
+
+/* Login Page */
+
+.login.page {
+  background-color: #000;
+}
+
+.login.page .form {
+  height: 100px;
+  margin-top: -100px;
+  position: absolute;
+
+  text-align: center;
+  top: 50%;
+  width: 100%;
+}
+
+.login.page .form .usernameInput {
+  background-color: transparent;
+  border: none;
+  border-bottom: 2px solid #fff;
+  outline: none;
+  padding-bottom: 15px;
+  text-align: center;
+  width: 400px;
+}
+
+.login.page .title {
+  font-size: 200%;
+}
+
+.login.page .usernameInput {
+  font-size: 200%;
+  letter-spacing: 3px;
+}
+
+.login.page .title, .login.page .usernameInput {
+  color: #fff;
+  font-weight: 100;
+}
+
+/* Chat page */
+
+.chat.page {
+  display: none;
+}
+
+/* Font */
+
+.messages {
+  font-size: 150%;
+}
+
+.inputMessage {
+  font-size: 100%;
+}
+
+.log {
+  color: gray;
+  font-size: 70%;
+  margin: 5px;
+  text-align: center;
+}
+
+/* Messages */
+
+.chatArea {
+  height: 100%;
+  padding-bottom: 60px;
+}
+
+.messages {
+  height: 100%;
+  margin: 0;
+  overflow-y: scroll;
+  padding: 10px 20px 10px 20px;
+}
+
+.message.typing .messageBody {
+  color: gray;
+}
+
+.username {
+  font-weight: 700;
+  overflow: hidden;
+  padding-right: 15px;
+  text-align: right;
+}
+
+/* Input */
+
+.inputMessage {
+  border: 10px solid #000;
+  bottom: 0;
+  height: 60px;
+  left: 0;
+  outline: none;
+  padding-left: 10px;
+  position: absolute;
+  right: 0;
+  width: 100%;
+}

examples/cluster-traefik/traefik.yml

@@ -0,0 +1,10 @@
+
+api:
+  insecure: true
+
+entryPoints:
+  web:
+    address: ":80"
+
+providers:
+  docker: {}

examples/private-messaging/.gitignore

@@ -0,0 +1,24 @@
+.DS_Store
+node_modules
+/dist
+
+
+# local env files
+.env.local
+.env.*.local
+
+# Log files
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+
+# Editor directories and files
+.idea
+.vscode
+*.suo
+*.ntvs*
+*.njsproj
+*.sln
+*.sw?
+package-lock.json

examples/private-messaging/README.md

@@ -0,0 +1,23 @@
+# Private messaging with Socket.IO
+
+Please read the related guide:
+
+- [Part I](https://socket.io/get-started/private-messaging-part-1/): initial implementation
+- [Part II](https://socket.io/get-started/private-messaging-part-2/): persistent user ID
+- [Part III](https://socket.io/get-started/private-messaging-part-3/): persistent messages
+- [Part IV](https://socket.io/get-started/private-messaging-part-4/): scaling up
+
+## Running the frontend
+
+```
+npm install
+npm run serve
+```
+
+### Running the server
+
+```
+cd server
+npm install
+npm start
+```

examples/private-messaging/babel.config.js

@@ -0,0 +1,5 @@
+module.exports = {
+  presets: [
+    '@vue/cli-plugin-babel/preset'
+  ]
+}

examples/private-messaging/package.json

@@ -0,0 +1,43 @@
+{
+  "name": "private-messaging",
+  "version": "0.1.0",
+  "private": true,
+  "scripts": {
+    "serve": "vue-cli-service serve",
+    "build": "vue-cli-service build",
+    "lint": "vue-cli-service lint"
+  },
+  "dependencies": {
+    "core-js": "^3.6.5",
+    "socket.io-client": "^3.1.1",
+    "vue": "^2.6.11"
+  },
+  "devDependencies": {
+    "@vue/cli-plugin-babel": "~4.5.0",
+    "@vue/cli-plugin-eslint": "~4.5.0",
+    "@vue/cli-service": "~4.5.0",
+    "babel-eslint": "^10.1.0",
+    "eslint": "^6.7.2",
+    "eslint-plugin-vue": "^6.2.2",
+    "vue-template-compiler": "^2.6.11"
+  },
+  "eslintConfig": {
+    "root": true,
+    "env": {
+      "node": true
+    },
+    "extends": [
+      "plugin:vue/essential",
+      "eslint:recommended"
+    ],
+    "parserOptions": {
+      "parser": "babel-eslint"
+    },
+    "rules": {}
+  },
+  "browserslist": [
+    "> 1%",
+    "last 2 versions",
+    "not dead"
+  ]
+}

examples/private-messaging/public/index.html

@@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<html lang="">
+  <head>
+    <meta charset="utf-8">
+    <meta http-equiv="X-UA-Compatible" content="IE=edge">
+    <meta name="viewport" content="width=device-width,initial-scale=1.0">
+    <link rel="icon" href="<%= BASE_URL %>favicon.ico">
+    <title>Private messaging with Socket.IO</title>
+  </head>
+  <body>
+    <noscript>
+      <strong>We're sorry but this application doesn't work properly without JavaScript enabled. Please enable it to continue.</strong>
+    </noscript>
+    <div id="app"></div>
+    <!-- built files will be auto injected -->
+  </body>
+</html>

examples/private-messaging/server/cluster.js

@@ -0,0 +1,31 @@
+const cluster = require("cluster");
+const http = require("http");
+const { setupMaster } = require("@socket.io/sticky");
+
+const WORKERS_COUNT = 4;
+
+if (cluster.isMaster) {
+  console.log(`Master ${process.pid} is running`);
+
+  for (let i = 0; i < WORKERS_COUNT; i++) {
+    cluster.fork();
+  }
+
+  cluster.on("exit", (worker) => {
+    console.log(`Worker ${worker.process.pid} died`);
+    cluster.fork();
+  });
+
+  const httpServer = http.createServer();
+  setupMaster(httpServer, {
+    loadBalancingMethod: "least-connection", // either "random", "round-robin" or "least-connection"
+  });
+  const PORT = process.env.PORT || 3000;
+
+  httpServer.listen(PORT, () =>
+    console.log(`server listening at http://localhost:${PORT}`)
+  );
+} else {
+  console.log(`Worker ${process.pid} started`);
+  require("./index");
+}

examples/private-messaging/server/docker-compose.yml

@@ -0,0 +1,7 @@
+version: "3"
+
+services:
+  redis:
+    image: redis:5
+    ports:
+      - "6379:6379"

examples/private-messaging/server/index.js

@@ -0,0 +1,125 @@
+const httpServer = require("http").createServer();
+const Redis = require("ioredis");
+const redisClient = new Redis();
+const io = require("socket.io")(httpServer, {
+  cors: {
+    origin: "http://localhost:8080",
+  },
+  adapter: require("socket.io-redis")({
+    pubClient: redisClient,
+    subClient: redisClient.duplicate(),
+  }),
+});
+
+const { setupWorker } = require("@socket.io/sticky");
+const crypto = require("crypto");
+const randomId = () => crypto.randomBytes(8).toString("hex");
+
+const { RedisSessionStore } = require("./sessionStore");
+const sessionStore = new RedisSessionStore(redisClient);
+
+const { RedisMessageStore } = require("./messageStore");
+const messageStore = new RedisMessageStore(redisClient);
+
+io.use(async (socket, next) => {
+  const sessionID = socket.handshake.auth.sessionID;
+  if (sessionID) {
+    const session = await sessionStore.findSession(sessionID);
+    if (session) {
+      socket.sessionID = sessionID;
+      socket.userID = session.userID;
+      socket.username = session.username;
+      return next();
+    }
+  }
+  const username = socket.handshake.auth.username;
+  if (!username) {
+    return next(new Error("invalid username"));
+  }
+  socket.sessionID = randomId();
+  socket.userID = randomId();
+  socket.username = username;
+  next();
+});
+
+io.on("connection", async (socket) => {
+  // persist session
+  sessionStore.saveSession(socket.sessionID, {
+    userID: socket.userID,
+    username: socket.username,
+    connected: true,
+  });
+
+  // emit session details
+  socket.emit("session", {
+    sessionID: socket.sessionID,
+    userID: socket.userID,
+  });
+
+  // join the "userID" room
+  socket.join(socket.userID);
+
+  // fetch existing users
+  const users = [];
+  const [messages, sessions] = await Promise.all([
+    messageStore.findMessagesForUser(socket.userID),
+    sessionStore.findAllSessions(),
+  ]);
+  const messagesPerUser = new Map();
+  messages.forEach((message) => {
+    const { from, to } = message;
+    const otherUser = socket.userID === from ? to : from;
+    if (messagesPerUser.has(otherUser)) {
+      messagesPerUser.get(otherUser).push(message);
+    } else {
+      messagesPerUser.set(otherUser, [message]);
+    }
+  });
+
+  sessions.forEach((session) => {
+    users.push({
+      userID: session.userID,
+      username: session.username,
+      connected: session.connected,
+      messages: messagesPerUser.get(session.userID) || [],
+    });
+  });
+  socket.emit("users", users);
+
+  // notify existing users
+  socket.broadcast.emit("user connected", {
+    userID: socket.userID,
+    username: socket.username,
+    connected: true,
+    messages: [],
+  });
+
+  // forward the private message to the right recipient (and to other tabs of the sender)
+  socket.on("private message", ({ content, to }) => {
+    const message = {
+      content,
+      from: socket.userID,
+      to,
+    };
+    socket.to(to).to(socket.userID).emit("private message", message);
+    messageStore.saveMessage(message);
+  });
+
+  // notify users upon disconnection
+  socket.on("disconnect", async () => {
+    const matchingSockets = await io.in(socket.userID).allSockets();
+    const isDisconnected = matchingSockets.size === 0;
+    if (isDisconnected) {
+      // notify other users
+      socket.broadcast.emit("user disconnected", socket.userID);
+      // update the connection status of the session
+      sessionStore.saveSession(socket.sessionID, {
+        userID: socket.userID,
+        username: socket.username,
+        connected: false,
+      });
+    }
+  });
+});
+
+setupWorker(io);

examples/private-messaging/server/messageStore.js

@@ -0,0 +1,54 @@
+/* abstract */ class MessageStore {
+  saveMessage(message) {}
+  findMessagesForUser(userID) {}
+}
+
+class InMemoryMessageStore extends MessageStore {
+  constructor() {
+    super();
+    this.messages = [];
+  }
+
+  saveMessage(message) {
+    this.messages.push(message);
+  }
+
+  findMessagesForUser(userID) {
+    return this.messages.filter(
+      ({ from, to }) => from === userID || to === userID
+    );
+  }
+}
+
+const CONVERSATION_TTL = 24 * 60 * 60;
+
+class RedisMessageStore extends MessageStore {
+  constructor(redisClient) {
+    super();
+    this.redisClient = redisClient;
+  }
+
+  saveMessage(message) {
+    const value = JSON.stringify(message);
+    this.redisClient
+      .multi()
+      .rpush(`messages:${message.from}`, value)
+      .rpush(`messages:${message.to}`, value)
+      .expire(`messages:${message.from}`, CONVERSATION_TTL)
+      .expire(`messages:${message.to}`, CONVERSATION_TTL)
+      .exec();
+  }
+
+  findMessagesForUser(userID) {
+    return this.redisClient
+      .lrange(`messages:${userID}`, 0, -1)
+      .then((results) => {
+        return results.map((result) => JSON.parse(result));
+      });
+  }
+}
+
+module.exports = {
+  InMemoryMessageStore,
+  RedisMessageStore,
+};

examples/private-messaging/server/package.json

@@ -0,0 +1,17 @@
+{
+  "name": "server",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "start": "node cluster.js"
+  },
+  "author": "Damien Arrachequesne <damien.arrachequesne@gmail.com>",
+  "license": "MIT",
+  "dependencies": {
+    "@socket.io/sticky": "^1.0.0",
+    "ioredis": "^4.22.0",
+    "socket.io": "^3.1.1",
+    "socket.io-redis": "^6.0.1"
+  }
+}

examples/private-messaging/server/sessionStore.js

@@ -0,0 +1,89 @@
+/* abstract */ class SessionStore {
+  findSession(id) {}
+  saveSession(id, session) {}
+  findAllSessions() {}
+}
+
+class InMemorySessionStore extends SessionStore {
+  constructor() {
+    super();
+    this.sessions = new Map();
+  }
+
+  findSession(id) {
+    return this.sessions.get(id);
+  }
+
+  saveSession(id, session) {
+    this.sessions.set(id, session);
+  }
+
+  findAllSessions() {
+    return [...this.sessions.values()];
+  }
+}
+
+const SESSION_TTL = 24 * 60 * 60;
+const mapSession = ([userID, username, connected]) =>
+  userID ? { userID, username, connected: connected === "true" } : undefined;
+
+class RedisSessionStore extends SessionStore {
+  constructor(redisClient) {
+    super();
+    this.redisClient = redisClient;
+  }
+
+  findSession(id) {
+    return this.redisClient
+      .hmget(`session:${id}`, "userID", "username", "connected")
+      .then(mapSession);
+  }
+
+  saveSession(id, { userID, username, connected }) {
+    this.redisClient
+      .multi()
+      .hset(
+        `session:${id}`,
+        "userID",
+        userID,
+        "username",
+        username,
+        "connected",
+        connected
+      )
+      .expire(`session:${id}`, SESSION_TTL)
+      .exec();
+  }
+
+  async findAllSessions() {
+    const keys = new Set();
+    let nextIndex = 0;
+    do {
+      const [nextIndexAsStr, results] = await this.redisClient.scan(
+        nextIndex,
+        "MATCH",
+        "session:*",
+        "COUNT",
+        "100"
+      );
+      nextIndex = parseInt(nextIndexAsStr, 10);
+      results.forEach((s) => keys.add(s));
+    } while (nextIndex !== 0);
+    const commands = [];
+    keys.forEach((key) => {
+      commands.push(["hmget", key, "userID", "username", "connected"]);
+    });
+    return this.redisClient
+      .multi(commands)
+      .exec()
+      .then((results) => {
+        return results
+          .map(([err, session]) => (err ? undefined : mapSession(session)))
+          .filter((v) => !!v);
+      });
+  }
+}
+module.exports = {
+  InMemorySessionStore,
+  RedisSessionStore,
+};

examples/private-messaging/src/App.vue

@@ -0,0 +1,78 @@
+<template>
+  <div id="app">
+    <select-username
+      v-if="!usernameAlreadySelected"
+      @input="onUsernameSelection"
+    />
+    <chat v-else />
+  </div>
+</template>
+
+<script>
+import SelectUsername from "./components/SelectUsername";
+import Chat from "./components/Chat";
+import socket from "./socket";
+
+export default {
+  name: "App",
+  components: {
+    Chat,
+    SelectUsername,
+  },
+  data() {
+    return {
+      usernameAlreadySelected: false,
+    };
+  },
+  methods: {
+    onUsernameSelection(username) {
+      this.usernameAlreadySelected = true;
+      socket.auth = { username };
+      socket.connect();
+    },
+  },
+  created() {
+    const sessionID = localStorage.getItem("sessionID");
+
+    if (sessionID) {
+      this.usernameAlreadySelected = true;
+      socket.auth = { sessionID };
+      socket.connect();
+    }
+
+    socket.on("session", ({ sessionID, userID }) => {
+      // attach the session ID to the next reconnection attempts
+      socket.auth = { sessionID };
+      // store it in the localStorage
+      localStorage.setItem("sessionID", sessionID);
+      // save the ID of the user
+      socket.userID = userID;
+    });
+
+    socket.on("connect_error", (err) => {
+      if (err.message === "invalid username") {
+        this.usernameAlreadySelected = false;
+      }
+    });
+  },
+  destroyed() {
+    socket.off("connect_error");
+  },
+};
+</script>
+
+<style>
+body {
+  margin: 0;
+}
+
+@font-face {
+  font-family: Lato;
+  src: url("/fonts/Lato-Regular.ttf");
+}
+
+#app {
+  font-family: Lato, Arial, sans-serif;
+  font-size: 14px;
+}
+</style>

examples/private-messaging/src/components/Chat.vue

@@ -0,0 +1,165 @@
+<template>
+  <div>
+    <div class="left-panel">
+      <user
+        v-for="user in users"
+        :key="user.userID"
+        :user="user"
+        :selected="selectedUser === user"
+        @select="onSelectUser(user)"
+      />
+    </div>
+    <message-panel
+      v-if="selectedUser"
+      :user="selectedUser"
+      @input="onMessage"
+      class="right-panel"
+    />
+  </div>
+</template>
+
+<script>
+import socket from "../socket";
+import User from "./User";
+import MessagePanel from "./MessagePanel";
+
+export default {
+  name: "Chat",
+  components: { User, MessagePanel },
+  data() {
+    return {
+      selectedUser: null,
+      users: [],
+    };
+  },
+  methods: {
+    onMessage(content) {
+      if (this.selectedUser) {
+        socket.emit("private message", {
+          content,
+          to: this.selectedUser.userID,
+        });
+        this.selectedUser.messages.push({
+          content,
+          fromSelf: true,
+        });
+      }
+    },
+    onSelectUser(user) {
+      this.selectedUser = user;
+      user.hasNewMessages = false;
+    },
+  },
+  created() {
+    socket.on("connect", () => {
+      this.users.forEach((user) => {
+        if (user.self) {
+          user.connected = true;
+        }
+      });
+    });
+
+    socket.on("disconnect", () => {
+      this.users.forEach((user) => {
+        if (user.self) {
+          user.connected = false;
+        }
+      });
+    });
+
+    const initReactiveProperties = (user) => {
+      user.hasNewMessages = false;
+    };
+
+    socket.on("users", (users) => {
+      users.forEach((user) => {
+        user.messages.forEach((message) => {
+          message.fromSelf = message.from === socket.userID;
+        });
+        for (let i = 0; i < this.users.length; i++) {
+          const existingUser = this.users[i];
+          if (existingUser.userID === user.userID) {
+            existingUser.connected = user.connected;
+            existingUser.messages = user.messages;
+            return;
+          }
+        }
+        user.self = user.userID === socket.userID;
+        initReactiveProperties(user);
+        this.users.push(user);
+      });
+      // put the current user first, and sort by username
+      this.users.sort((a, b) => {
+        if (a.self) return -1;
+        if (b.self) return 1;
+        if (a.username < b.username) return -1;
+        return a.username > b.username ? 1 : 0;
+      });
+    });
+
+    socket.on("user connected", (user) => {
+      for (let i = 0; i < this.users.length; i++) {
+        const existingUser = this.users[i];
+        if (existingUser.userID === user.userID) {
+          existingUser.connected = true;
+          return;
+        }
+      }
+      initReactiveProperties(user);
+      this.users.push(user);
+    });
+
+    socket.on("user disconnected", (id) => {
+      for (let i = 0; i < this.users.length; i++) {
+        const user = this.users[i];
+        if (user.userID === id) {
+          user.connected = false;
+          break;
+        }
+      }
+    });
+
+    socket.on("private message", ({ content, from, to }) => {
+      for (let i = 0; i < this.users.length; i++) {
+        const user = this.users[i];
+        const fromSelf = socket.userID === from;
+        if (user.userID === (fromSelf ? to : from)) {
+          user.messages.push({
+            content,
+            fromSelf,
+          });
+          if (user !== this.selectedUser) {
+            user.hasNewMessages = true;
+          }
+          break;
+        }
+      }
+    });
+  },
+  destroyed() {
+    socket.off("connect");
+    socket.off("disconnect");
+    socket.off("users");
+    socket.off("user connected");
+    socket.off("user disconnected");
+    socket.off("private message");
+  },
+};
+</script>
+
+<style scoped>
+.left-panel {
+  position: fixed;
+  left: 0;
+  top: 0;
+  bottom: 0;
+  width: 260px;
+  overflow-x: hidden;
+  background-color: #3f0e40;
+  color: white;
+}
+
+.right-panel {
+  margin-left: 260px;
+}
+</style>

examples/private-messaging/src/components/MessagePanel.vue

@@ -0,0 +1,101 @@
+<template>
+  <div>
+    <div class="header">
+      <status-icon :connected="user.connected" />{{ user.username }}
+    </div>
+
+    <ul class="messages">
+      <li
+        v-for="(message, index) in user.messages"
+        :key="index"
+        class="message"
+      >
+        <div v-if="displaySender(message, index)" class="sender">
+          {{ message.fromSelf ? "(yourself)" : user.username }}
+        </div>
+        {{ message.content }}
+      </li>
+    </ul>
+
+    <form @submit.prevent="onSubmit" class="form">
+      <textarea v-model="input" placeholder="Your message..." class="input" />
+      <button :disabled="!isValid" class="send-button">Send</button>
+    </form>
+  </div>
+</template>
+
+<script>
+import StatusIcon from "./StatusIcon";
+
+export default {
+  name: "MessagePanel",
+  components: {
+    StatusIcon,
+  },
+  props: {
+    user: Object,
+  },
+  data() {
+    return {
+      input: "",
+    };
+  },
+  methods: {
+    onSubmit() {
+      this.$emit("input", this.input);
+      this.input = "";
+    },
+    displaySender(message, index) {
+      return (
+        index === 0 ||
+        this.user.messages[index - 1].fromSelf !==
+          this.user.messages[index].fromSelf
+      );
+    },
+  },
+  computed: {
+    isValid() {
+      return this.input.length > 0;
+    },
+  },
+};
+</script>
+
+<style scoped>
+.header {
+  line-height: 40px;
+  padding: 10px 20px;
+  border-bottom: 1px solid #dddddd;
+}
+
+.messages {
+  margin: 0;
+  padding: 20px;
+}
+
+.message {
+  list-style: none;
+}
+
+.sender {
+  font-weight: bold;
+  margin-top: 5px;
+}
+
+.form {
+  padding: 10px;
+}
+
+.input {
+  width: 80%;
+  resize: none;
+  padding: 10px;
+  line-height: 1.5;
+  border-radius: 5px;
+  border: 1px solid #000;
+}
+
+.send-button {
+  vertical-align: top;
+}
+</style>

examples/private-messaging/src/components/SelectUsername.vue

@@ -0,0 +1,36 @@
+<template>
+  <div class="select-username">
+    <form @submit.prevent="onSubmit">
+      <input v-model="username" placeholder="Your username..." />
+      <button :disabled="!isValid">Send</button>
+    </form>
+  </div>
+</template>
+
+<script>
+export default {
+  name: "SelectUsername",
+  data() {
+    return {
+      username: "",
+    };
+  },
+  computed: {
+    isValid() {
+      return this.username.length > 2;
+    },
+  },
+  methods: {
+    onSubmit() {
+      this.$emit("input", this.username);
+    },
+  },
+};
+</script>
+
+<style scoped>
+.select-username {
+  width: 300px;
+  margin: 200px auto 0;
+}
+</style>

examples/private-messaging/src/components/StatusIcon.vue

@@ -0,0 +1,27 @@
+<template>
+  <i class="icon" :class="{ connected: connected }"></i>
+</template>
+
+<script>
+export default {
+  name: "StatusIcon",
+  props: {
+    connected: Boolean,
+  },
+};
+</script>
+
+<style scoped>
+.icon {
+  height: 8px;
+  width: 8px;
+  border-radius: 50%;
+  display: inline-block;
+  background-color: #e38968;
+  margin-right: 6px;
+}
+
+.icon.connected {
+  background-color: #86bb71;
+}
+</style>

examples/private-messaging/src/components/User.vue

@@ -0,0 +1,63 @@
+<template>
+  <div class="user" @click="onClick" :class="{ selected: selected }">
+    <div class="description">
+      <div class="name">
+        {{ user.username }} {{ user.self ? " (yourself)" : "" }}
+      </div>
+      <div class="status">
+        <status-icon :connected="user.connected" />{{ status }}
+      </div>
+    </div>
+    <div v-if="user.hasNewMessages" class="new-messages">!</div>
+  </div>
+</template>
+
+<script>
+import StatusIcon from "./StatusIcon";
+export default {
+  name: "User",
+  components: { StatusIcon },
+  props: {
+    user: Object,
+    selected: Boolean,
+  },
+  methods: {
+    onClick() {
+      this.$emit("select");
+    },
+  },
+  computed: {
+    status() {
+      return this.user.connected ? "online" : "offline";
+    },
+  },
+};
+</script>
+
+<style scoped>
+.selected {
+  background-color: #1164a3;
+}
+
+.user {
+  padding: 10px;
+}
+
+.description {
+  display: inline-block;
+}
+
+.status {
+  color: #92959e;
+}
+
+.new-messages {
+  color: white;
+  background-color: red;
+  width: 20px;
+  border-radius: 5px;
+  text-align: center;
+  float: right;
+  margin-top: 10px;
+}
+</style>

examples/private-messaging/src/main.js

@@ -0,0 +1,8 @@
+import Vue from "vue";
+import App from "./App.vue";
+
+Vue.config.productionTip = false;
+
+new Vue({
+  render: (h) => h(App),
+}).$mount("#app");

examples/private-messaging/src/socket.js

@@ -0,0 +1,10 @@
+import { io } from "socket.io-client";
+
+const URL = "http://localhost:3000";
+const socket = io(URL, { autoConnect: false });
+
+socket.onAny((event, ...args) => {
+  console.log(event, args);
+});
+
+export default socket;

examples/typescript/client.ts

@@ -1,7 +1,6 @@
-import { Manager } from "socket.io-client";
+import { io } from "socket.io-client";
 
-const manager = new Manager("ws://localhost:8080");
-const socket = manager.socket("/");
+const socket = io("ws://localhost:8080/", {});
 
 socket.on("connect", () => {
     console.log(`connect ${socket.id}`);

examples/typescript/package-lock.json

@@ -9,6 +9,21 @@
       "resolved": "https://registry.npmjs.org/@types/component-emitter/-/component-emitter-1.2.10.tgz",
       "integrity": "sha512-bsjleuRKWmGqajMerkzox19aGbscQX5rmmvvXl3wlIp5gMG1HgkiwPxsN5p070fBDKTNSPgojVbuY1+HWMbFhg=="
     },
+    "@types/cookie": {
+      "version": "0.4.0",
+      "resolved": "https://registry.npmjs.org/@types/cookie/-/cookie-0.4.0.tgz",
+      "integrity": "sha512-y7mImlc/rNkvCRmg8gC3/lj87S7pTUIJ6QGjwHR9WQJcFs+ZMTOaoPrkdFA/YdbuqVEmEbb5RdhVxMkAcgOnpg=="
+    },
+    "@types/cors": {
+      "version": "2.8.9",
+      "resolved": "https://registry.npmjs.org/@types/cors/-/cors-2.8.9.tgz",
+      "integrity": "sha512-zurD1ibz21BRlAOIKP8yhrxlqKx6L9VCwkB5kMiP6nZAhoF5MvC7qS1qPA7nRcr1GJolfkQC7/EAL4hdYejLtg=="
+    },
+    "@types/node": {
+      "version": "14.14.16",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-14.14.16.tgz",
+      "integrity": "sha512-naXYePhweTi+BMv11TgioE2/FXU4fSl29HAH1ffxVciNsH3rYXjNP2yM8wqmSm7jS20gM8TIklKiTen+1iVncw=="
+    },
     "accepts": {
       "version": "1.3.7",
       "resolved": "https://registry.npmjs.org/accepts/-/accepts-1.3.7.tgz",
@@ -81,9 +96,9 @@
       "integrity": "sha512-58lmxKSA4BNyLz+HHMUzlOEpg09FV+ev6ZMe3vJihgdxzgcwZ8VoEEPmALCZG9LmqfVoNMMKpttIYTVG6uDY7A=="
     },
     "engine.io": {
-      "version": "4.0.2",
-      "resolved": "https://registry.npmjs.org/engine.io/-/engine.io-4.0.2.tgz",
-      "integrity": "sha512-sumdttqWLNjbuSMOSgDdL2xiEld9s5QZDk9VLyr4e28o+lzNNADhU3qpQDAY7cm2VZH0Otw/U0fL8mEjZ6kBMg==",
+      "version": "4.0.5",
+      "resolved": "https://registry.npmjs.org/engine.io/-/engine.io-4.0.5.tgz",
+      "integrity": "sha512-Ri+whTNr2PKklxQkfbGjwEo+kCBUM4Qxk4wtLqLrhH+b1up2NFL9g9pjYWiCV/oazwB0rArnvF/ZmZN2ab5Hpg==",
       "requires": {
         "accepts": "~1.3.4",
         "base64id": "2.0.0",
@@ -95,9 +110,9 @@
       }
     },
     "engine.io-client": {
-      "version": "4.0.2",
-      "resolved": "https://registry.npmjs.org/engine.io-client/-/engine.io-client-4.0.2.tgz",
-      "integrity": "sha512-cfzFu0u7rr/Gmz/CefwZ6mBj9kxtsOtOavV/YLbn+2sPGE1ZTSWh3tj8427a0od+BK27zsWDpnDx98fnpnmksA==",
+      "version": "4.0.5",
+      "resolved": "https://registry.npmjs.org/engine.io-client/-/engine.io-client-4.0.5.tgz",
+      "integrity": "sha512-1lkn0QdekHQPMTcxUh8LqIuxQHNtKV5GvqkQzmZ1rYKAvB6puMm13U7K1ps3OQZ4joE46asQiAKrcdL9weNEVw==",
       "requires": {
         "base64-arraybuffer": "0.1.4",
         "component-emitter": "~1.3.0",
@@ -119,9 +134,12 @@
       }
     },
     "engine.io-parser": {
-      "version": "4.0.1",
-      "resolved": "https://registry.npmjs.org/engine.io-parser/-/engine.io-parser-4.0.1.tgz",
-      "integrity": "sha512-v5aZK1hlckcJDGmHz3W8xvI3NUHYc9t8QtTbqdR5OaH3S9iJZilPubauOm+vLWOMMWzpE3hiq92l9lTAHamRCg=="
+      "version": "4.0.2",
+      "resolved": "https://registry.npmjs.org/engine.io-parser/-/engine.io-parser-4.0.2.tgz",
+      "integrity": "sha512-sHfEQv6nmtJrq6TKuIz5kyEKH/qSdK56H/A+7DnAuUPWosnIZAS2NHNcPLmyjtY3cGS/MqJdZbUjW97JU72iYg==",
+      "requires": {
+        "base64-arraybuffer": "0.1.4"
+      }
     },
     "has-cors": {
       "version": "1.1.0",
@@ -147,9 +165,9 @@
       }
     },
     "ms": {
-      "version": "2.1.2",
-      "resolved": "https://registry.npmjs.org/ms/-/ms-2.1.2.tgz",
-      "integrity": "sha512-sGkPx+VjMtmA6MX27oA4FBFELFCZZ4S4XqeGOXCv68tT+jb3vk/RyaKWP0PTKyWtmLSM0b+adUTEvbs1PEaH2w=="
+      "version": "2.1.3",
+      "resolved": "https://registry.npmjs.org/ms/-/ms-2.1.3.tgz",
+      "integrity": "sha512-6FlzubTLZG3J2a/NVCAleEhjzq5oxgHyaCU9yYXvcLsvoVaHJq/s5xXI6/XXP6tz7R9xAOtHnSO/tXtF3WRTlA=="
     },
     "negotiator": {
       "version": "0.6.2",
@@ -172,10 +190,13 @@
       "integrity": "sha512-AUjen8sAkGgao7UyCX6Ahv0gIK2fABKmYjvP4xmy5JaKvcbTRueIqIPHLAfq30xJddqSE033IOMUSOMCcK3Sow=="
     },
     "socket.io": {
-      "version": "3.0.1",
-      "resolved": "https://registry.npmjs.org/socket.io/-/socket.io-3.0.1.tgz",
-      "integrity": "sha512-oVYbCQ4sCwm4wVi+f1bsE3YFXcvd6b4JjVP8D7IZnQqBeJOKX9XrdgJWSbXqBEqUXPY3jdTqb1M3s4KFTa/IHg==",
+      "version": "3.0.4",
+      "resolved": "https://registry.npmjs.org/socket.io/-/socket.io-3.0.4.tgz",
+      "integrity": "sha512-Vj1jUoO75WGc9txWd311ZJJqS9Dr8QtNJJ7gk2r7dcM/yGe9sit7qOijQl3GAwhpBOz/W8CwkD7R6yob07nLbA==",
       "requires": {
+        "@types/cookie": "^0.4.0",
+        "@types/cors": "^2.8.8",
+        "@types/node": "^14.14.7",
         "accepts": "~1.3.4",
         "base64id": "~2.0.0",
         "debug": "~4.1.0",
@@ -190,9 +211,9 @@
       "integrity": "sha512-2wo4EXgxOGSFueqvHAdnmi5JLZzWqMArjuP4nqC26AtLh5PoCPsaRbRdah2xhcwTAMooZfjYiNVNkkmmSMaxOQ=="
     },
     "socket.io-client": {
-      "version": "3.0.1",
-      "resolved": "https://registry.npmjs.org/socket.io-client/-/socket.io-client-3.0.1.tgz",
-      "integrity": "sha512-iIzWRDrF/h3KPtHjvLt5LL/1n7Euvv35zVa1r10ScRjVw40yc8DxFj7GnKrj1RNYkbtveWOwEsy2lWp3oFJO7w==",
+      "version": "3.0.4",
+      "resolved": "https://registry.npmjs.org/socket.io-client/-/socket.io-client-3.0.4.tgz",
+      "integrity": "sha512-qMvBuS+W9JIN2mkfAWDCxuIt+jpIKDf8C0604zEqx1JrPaPSS6cN0F3B2GYWC83TqBeVJXW66GFxWV3KD88n0Q==",
       "requires": {
         "@types/component-emitter": "^1.2.10",
         "backo2": "1.0.2",
@@ -205,10 +226,11 @@
       }
     },
     "socket.io-parser": {
-      "version": "4.0.1",
-      "resolved": "https://registry.npmjs.org/socket.io-parser/-/socket.io-parser-4.0.1.tgz",
-      "integrity": "sha512-5JfNykYptCwU2lkOI0ieoePWm+6stEhkZ2UnLDjqnE1YEjUlXXLd1lpxPZ+g+h3rtaytwWkWrLQCaJULlGqjOg==",
+      "version": "4.0.2",
+      "resolved": "https://registry.npmjs.org/socket.io-parser/-/socket.io-parser-4.0.2.tgz",
+      "integrity": "sha512-Bs3IYHDivwf+bAAuW/8xwJgIiBNtlvnjYRc4PbXgniLmcP1BrakBoq/QhO24rgtgW7VZ7uAaswRGxutUnlAK7g==",
       "requires": {
+        "@types/component-emitter": "^1.2.10",
         "component-emitter": "~1.3.0",
         "debug": "~4.1.0"
       }
@@ -250,9 +272,9 @@
       "integrity": "sha1-IpnwLG3tMNSllhsLn3RSShj2NPw="
     },
     "ws": {
-      "version": "7.4.0",
-      "resolved": "https://registry.npmjs.org/ws/-/ws-7.4.0.tgz",
-      "integrity": "sha512-kyFwXuV/5ymf+IXhS6f0+eAFvydbaBW3zjpT6hUdAh/hbVjTIB5EHBGi0bPoCLSK2wcuz3BrEkB9LrYv1Nm4NQ=="
+      "version": "7.4.2",
+      "resolved": "https://registry.npmjs.org/ws/-/ws-7.4.2.tgz",
+      "integrity": "sha512-T4tewALS3+qsrpGI/8dqNMLIVdq/g/85U98HPMa6F0m6xTbvhXU6RCQLqPH3+SlomNV/LdY6RXEbBpMH6EOJnA=="
     },
     "xmlhttprequest-ssl": {
       "version": "1.5.5",

examples/typescript/package.json

@@ -11,8 +11,8 @@
   "author": "Damien Arrachequesne",
   "license": "MIT",
   "dependencies": {
-    "socket.io": "^3.0.1",
-    "socket.io-client": "^3.0.1",
+    "socket.io": "^3.0.4",
+    "socket.io-client": "^3.0.4",
     "ts-node": "^9.0.0",
     "typescript": "^4.0.5"
   }

lib/client.ts

@@ -1,10 +1,10 @@
 import { Decoder, Encoder, Packet, PacketType } from "socket.io-parser";
 import debugModule = require("debug");
-import { IncomingMessage } from "http";
-import { Server } from "./index";
-import { Socket } from "./socket";
-import { SocketId } from "socket.io-adapter";
-import { ParentNamespace } from "./parent-namespace";
+import url = require("url");
+import type { IncomingMessage } from "http";
+import type { Namespace, Server } from "./index";
+import type { Socket } from "./socket";
+import type { SocketId } from "socket.io-adapter";
 
 const debug = debugModule("socket.io:client");
 
@@ -17,16 +17,16 @@ export class Client {
   private readonly decoder: Decoder;
   private sockets: Map<SocketId, Socket> = new Map();
   private nsps: Map<string, Socket> = new Map();
-  private connectTimeout: NodeJS.Timeout;
+  private connectTimeout?: NodeJS.Timeout;
 
   /**
    * Client constructor.
    *
-   * @param {Server} server instance
-   * @param {Socket} conn
+   * @param server instance
+   * @param conn
    * @package
    */
-  constructor(server: Server, conn) {
+  constructor(server: Server, conn: Socket) {
     this.server = server;
     this.conn = conn;
     this.encoder = server.encoder;
@@ -78,47 +78,52 @@ export class Client {
    * @param {Object} auth - the auth parameters
    * @private
    */
-  private connect(name: string, auth: object = {}) {
+  private connect(name: string, auth: object = {}): void {
     if (this.server._nsps.has(name)) {
       debug("connecting to namespace %s", name);
       return this.doConnect(name, auth);
     }
 
-    this.server._checkNamespace(name, auth, (dynamicNsp: ParentNamespace) => {
-      if (dynamicNsp) {
-        debug("dynamic namespace %s was created", dynamicNsp.name);
-        this.doConnect(name, auth);
-      } else {
-        debug("creation of namespace %s was denied", name);
-        this._packet({
-          type: PacketType.CONNECT_ERROR,
-          nsp: name,
-          data: {
-            message: "Invalid namespace"
-          }
-        });
+    this.server._checkNamespace(
+      name,
+      auth,
+      (dynamicNspName: Namespace | false) => {
+        if (dynamicNspName) {
+          debug("dynamic namespace %s was created", dynamicNspName);
+          this.doConnect(name, auth);
+        } else {
+          debug("creation of namespace %s was denied", name);
+          this._packet({
+            type: PacketType.CONNECT_ERROR,
+            nsp: name,
+            data: {
+              message: "Invalid namespace",
+            },
+          });
+        }
       }
-    });
+    );
   }
 
   /**
    * Connects a client to a namespace.
    *
-   * @param {String} name - the namespace
+   * @param name - the namespace
    * @param {Object} auth - the auth parameters
    *
    * @private
    */
-  private doConnect(name: string, auth: object) {
-    if (this.connectTimeout) {
-      clearTimeout(this.connectTimeout);
-      this.connectTimeout = null;
-    }
+  private doConnect(name: string, auth: object): void {
     const nsp = this.server.of(name);
 
     const socket = nsp._add(this, auth, () => {
       this.sockets.set(socket.id, socket);
       this.nsps.set(nsp.name, socket);
+
+      if (this.connectTimeout) {
+        clearTimeout(this.connectTimeout);
+        this.connectTimeout = undefined;
+      }
     });
   }
 
@@ -127,7 +132,7 @@ export class Client {
    *
    * @private
    */
-  _disconnect() {
+  _disconnect(): void {
     for (const socket of this.sockets.values()) {
       socket.disconnect();
     }
@@ -140,9 +145,9 @@ export class Client {
    *
    * @private
    */
-  _remove(socket: Socket) {
+  _remove(socket: Socket): void {
     if (this.sockets.has(socket.id)) {
-      const nsp = this.sockets.get(socket.id).nsp.name;
+      const nsp = this.sockets.get(socket.id)!.nsp.name;
       this.sockets.delete(socket.id);
       this.nsps.delete(nsp);
     } else {
@@ -155,8 +160,8 @@ export class Client {
    *
    * @private
    */
-  private close() {
-    if ("open" == this.conn.readyState) {
+  private close(): void {
+    if ("open" === this.conn.readyState) {
       debug("forcing transport close");
       this.conn.close();
       this.onclose("forced server close");
@@ -170,19 +175,20 @@ export class Client {
    * @param {Object} opts
    * @private
    */
-  _packet(packet, opts?) {
+  _packet(packet: Packet, opts?: any): void {
     opts = opts || {};
     const self = this;
 
     // this writes to the actual connection
-    function writeToEngine(encodedPackets) {
+    function writeToEngine(encodedPackets: any) {
+      // TODO clarify this.
       if (opts.volatile && !self.conn.transport.writable) return;
       for (let i = 0; i < encodedPackets.length; i++) {
         self.conn.write(encodedPackets[i], { compress: opts.compress });
       }
     }
 
-    if ("open" == this.conn.readyState) {
+    if ("open" === this.conn.readyState) {
       debug("writing packet %j", packet);
       if (!opts.preEncoded) {
         // not broadcasting, need to encode
@@ -201,7 +207,7 @@ export class Client {
    *
    * @private
    */
-  private ondata(data) {
+  private ondata(data): void {
     // try/catch is needed for protocol violations (GH-1880)
     try {
       this.decoder.add(data);
@@ -215,13 +221,18 @@ export class Client {
    *
    * @private
    */
-  private ondecoded(packet: Packet) {
-    if (PacketType.CONNECT == packet.type) {
-      this.connect(packet.nsp, packet.data);
+  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);
+      }
     } else {
       const socket = this.nsps.get(packet.nsp);
       if (socket) {
-        process.nextTick(function() {
+        process.nextTick(function () {
           socket._onpacket(packet);
         });
       } else {
@@ -236,7 +247,7 @@ export class Client {
    * @param {Object} err object
    * @private
    */
-  private onerror(err) {
+  private onerror(err): void {
     for (const socket of this.sockets.values()) {
       socket._onerror(err);
     }
@@ -249,7 +260,7 @@ export class Client {
    * @param reason
    * @private
    */
-  private onclose(reason: string) {
+  private onclose(reason: string): void {
     debug("client close with reason %s", reason);
 
     // ignore a potential subsequent `close` event
@@ -268,11 +279,16 @@ export class Client {
    * Cleans up event listeners.
    * @private
    */
-  private destroy() {
+  private destroy(): void {
     this.conn.removeListener("data", this.ondata);
     this.conn.removeListener("error", this.onerror);
     this.conn.removeListener("close", this.onclose);
     // @ts-ignore
     this.decoder.removeListener("decoded", this.ondecoded);
+
+    if (this.connectTimeout) {
+      clearTimeout(this.connectTimeout);
+      this.connectTimeout = undefined;
+    }
   }
 }

lib/index.ts

@@ -11,11 +11,11 @@ import { ExtendedError, Namespace } from "./namespace";
 import { ParentNamespace } from "./parent-namespace";
 import { Adapter, Room, SocketId } from "socket.io-adapter";
 import * as parser from "socket.io-parser";
-import { Encoder } from "socket.io-parser";
+import type { Encoder } from "socket.io-parser";
 import debugModule from "debug";
 import { Socket } from "./socket";
-import { CookieSerializeOptions } from "cookie";
-import { CorsOptions } from "cors";
+import type { CookieSerializeOptions } from "cookie";
+import type { CorsOptions } from "cors";
 
 const debug = debugModule("socket.io:server");
 
@@ -23,6 +23,11 @@ const clientVersion = require("../package.json").version;
 const dotMapRegex = /\.map/;
 
 type Transport = "polling" | "websocket";
+type ParentNspNameMatchFn = (
+  name: string,
+  auth: { [key: string]: any },
+  fn: (err: Error | null, success: boolean) => void
+) => void;
 
 interface EngineOptions {
   /**
@@ -95,6 +100,11 @@ interface EngineOptions {
    * the options that will be forwarded to the cors module
    */
   cors: CorsOptions;
+  /**
+   * whether to enable compatibility with Socket.IO v2 clients
+   * @default false
+   */
+  allowEIO3: boolean;
 }
 
 interface AttachOptions {
@@ -149,7 +159,7 @@ export class Server extends EventEmitter {
   public readonly sockets: Namespace;
 
   /** @private */
-  readonly _parser;
+  readonly _parser: typeof parser;
   /** @private */
   readonly encoder: Encoder;
 
@@ -157,17 +167,8 @@ export class Server extends EventEmitter {
    * @private
    */
   _nsps: Map<string, Namespace> = new Map();
-  private parentNsps: Map<
-    | string
-    | RegExp
-    | ((
-        name: string,
-        query: object,
-        fn: (err: Error, success: boolean) => void
-      ) => void),
-    ParentNamespace
-  > = new Map();
-  private _adapter: any;
+  private parentNsps: Map<ParentNspNameMatchFn, ParentNamespace> = new Map();
+  private _adapter?: typeof Adapter;
   private _serveClient: boolean;
   private opts: Partial<EngineOptions>;
   private eio;
@@ -184,18 +185,28 @@ export class Server extends EventEmitter {
   /**
    * Server constructor.
    *
-   * @param {http.Server|Number|Object} srv http server, port or options
-   * @param {Object} [opts]
+   * @param srv http server, port, or options
+   * @param [opts]
    * @public
    */
   constructor(opts?: Partial<ServerOptions>);
-  constructor(srv: http.Server, opts?: Partial<ServerOptions>);
-  constructor(srv: number, opts?: Partial<ServerOptions>);
-  constructor(srv?: any, opts: Partial<ServerOptions> = {}) {
+  constructor(srv?: http.Server | number, opts?: Partial<ServerOptions>);
+  constructor(
+    srv: undefined | Partial<ServerOptions> | http.Server | number,
+    opts?: Partial<ServerOptions>
+  );
+  constructor(
+    srv: undefined | Partial<ServerOptions> | http.Server | number,
+    opts: Partial<ServerOptions> = {}
+  ) {
     super();
-    if ("object" == typeof srv && srv instanceof Object && !srv.listen) {
-      opts = srv;
-      srv = null;
+    if (
+      "object" === typeof srv &&
+      srv instanceof Object &&
+      !(srv as Partial<http.Server>).listen
+    ) {
+      opts = srv as Partial<ServerOptions>;
+      srv = undefined;
     }
     this.path(opts.path || "/socket.io");
     this.connectTimeout(opts.connectTimeout || 45000);
@@ -205,44 +216,45 @@ export class Server extends EventEmitter {
     this.adapter(opts.adapter || Adapter);
     this.sockets = this.of("/");
     this.opts = opts;
-    if (srv) this.attach(srv);
+    if (srv) this.attach(srv as http.Server);
   }
 
   /**
    * Sets/gets whether client code is being served.
    *
-   * @param {Boolean} v - whether to serve client code
-   * @return {Server|Boolean} self when setting or value when getting
+   * @param v - whether to serve client code
+   * @return self when setting or value when getting
    * @public
    */
-  public serveClient(v: boolean): Server;
+  public serveClient(v: boolean): this;
   public serveClient(): boolean;
-  public serveClient(v?: boolean): Server | boolean {
+  public serveClient(v?: boolean): this | boolean;
+  public serveClient(v?: boolean): this | boolean {
     if (!arguments.length) return this._serveClient;
-    this._serveClient = v;
+    this._serveClient = v!;
     return this;
   }
 
   /**
    * Executes the middleware for an incoming namespace not already created on the server.
    *
-   * @param {String} name - name of incoming namespace
-   * @param {Object} auth - the auth parameters
-   * @param {Function} fn - callback
+   * @param name - name of incoming namespace
+   * @param auth - the auth parameters
+   * @param fn - callback
    *
    * @private
    */
   _checkNamespace(
     name: string,
-    auth: object,
-    fn: (nsp: Namespace | boolean) => void
-  ) {
+    auth: { [key: string]: any },
+    fn: (nsp: Namespace | false) => void
+  ): void {
     if (this.parentNsps.size === 0) return fn(false);
 
     const keysIterator = this.parentNsps.keys();
 
     const run = () => {
-      let nextFn = keysIterator.next();
+      const nextFn = keysIterator.next();
       if (nextFn.done) {
         return fn(false);
       }
@@ -250,7 +262,7 @@ export class Server extends EventEmitter {
         if (err || !allow) {
           run();
         } else {
-          fn(this.parentNsps.get(nextFn.value).createChild(name));
+          fn(this.parentNsps.get(nextFn.value)!.createChild(name));
         }
       });
     };
@@ -265,12 +277,13 @@ export class Server extends EventEmitter {
    * @return {Server|String} self when setting or value when getting
    * @public
    */
-  public path(v: string): Server;
+  public path(v: string): this;
   public path(): string;
-  public path(v?: string): Server | string {
+  public path(v?: string): this | string;
+  public path(v?: string): this | string {
     if (!arguments.length) return this._path;
 
-    this._path = v.replace(/\/$/, "");
+    this._path = v!.replace(/\/$/, "");
 
     const escapedPath = this._path.replace(/[-\/\\^$*+?.()|[\]{}]/g, "\\$&");
     this.clientPathRegex = new RegExp(
@@ -286,9 +299,10 @@ export class Server extends EventEmitter {
    * @param v
    * @public
    */
-  public connectTimeout(v: number): Server;
+  public connectTimeout(v: number): this;
   public connectTimeout(): number;
-  public connectTimeout(v?: number): Server | number {
+  public connectTimeout(v?: number): this | number;
+  public connectTimeout(v?: number): this | number {
     if (v === undefined) return this._connectTimeout;
     this._connectTimeout = v;
     return this;
@@ -297,13 +311,14 @@ export class Server extends EventEmitter {
   /**
    * Sets the adapter for rooms.
    *
-   * @param {Adapter} v pathname
-   * @return {Server|Adapter} self when setting or value when getting
+   * @param v pathname
+   * @return self when setting or value when getting
    * @public
    */
-  public adapter(): any;
-  public adapter(v: any);
-  public adapter(v?): Server | any {
+  public adapter(): typeof Adapter | undefined;
+  public adapter(v: typeof Adapter): this;
+  public adapter(v?: typeof Adapter): typeof Adapter | undefined | this;
+  public adapter(v?: typeof Adapter): typeof Adapter | undefined | this {
     if (!arguments.length) return this._adapter;
     this._adapter = v;
     for (const nsp of this._nsps.values()) {
@@ -315,28 +330,30 @@ export class Server extends EventEmitter {
   /**
    * Attaches socket.io to a server or port.
    *
-   * @param {http.Server|Number} srv - server or port
-   * @param {Object} opts - options passed to engine.io
-   * @return {Server} self
+   * @param srv - server or port
+   * @param opts - options passed to engine.io
+   * @return self
    * @public
    */
-  public listen(srv: http.Server, opts?: Partial<ServerOptions>): Server;
-  public listen(srv: number, opts?: Partial<ServerOptions>): Server;
-  public listen(srv: any, opts: Partial<ServerOptions> = {}): Server {
+  public listen(
+    srv: http.Server | number,
+    opts: Partial<ServerOptions> = {}
+  ): this {
     return this.attach(srv, opts);
   }
 
   /**
    * Attaches socket.io to a server or port.
    *
-   * @param {http.Server|Number} srv - server or port
-   * @param {Object} opts - options passed to engine.io
-   * @return {Server} self
+   * @param srv - server or port
+   * @param opts - options passed to engine.io
+   * @return self
    * @public
    */
-  public attach(srv: http.Server, opts?: Partial<ServerOptions>): Server;
-  public attach(port: number, opts?: Partial<ServerOptions>): Server;
-  public attach(srv: any, opts: Partial<ServerOptions> = {}): Server {
+  public attach(
+    srv: http.Server | number,
+    opts: Partial<ServerOptions> = {}
+  ): this {
     if ("function" == typeof srv) {
       const msg =
         "You are trying to attach socket.io to an express " +
@@ -376,7 +393,10 @@ export class Server extends EventEmitter {
    * @param opts - options passed to engine.io
    * @private
    */
-  private initEngine(srv: http.Server, opts: Partial<EngineAttachOptions>) {
+  private initEngine(
+    srv: http.Server,
+    opts: Partial<EngineAttachOptions>
+  ): void {
     // initialize engine
     debug("creating engine.io instance with opts %j", opts);
     this.eio = engine.attach(srv, opts);
@@ -394,10 +414,10 @@ export class Server extends EventEmitter {
   /**
    * Attaches the static file serving.
    *
-   * @param {Function|http.Server} srv http server
+   * @param srv http server
    * @private
    */
-  private attachServe(srv) {
+  private attachServe(srv: http.Server): void {
     debug("attaching client serving req handler");
 
     const evs = srv.listeners("request").slice(0);
@@ -416,22 +436,23 @@ export class Server extends EventEmitter {
   /**
    * Handles a request serving of client source and map
    *
-   * @param {http.IncomingMessage} req
-   * @param {http.ServerResponse} res
+   * @param req
+   * @param res
    * @private
    */
-  private serve(req: http.IncomingMessage, res: http.ServerResponse) {
-    const filename = req.url.replace(this._path, "");
+  private serve(req: http.IncomingMessage, res: http.ServerResponse): void {
+    const filename = req.url!.replace(this._path, "");
     const isMap = dotMapRegex.test(filename);
     const type = isMap ? "map" : "source";
 
     // Per the standard, ETags must be quoted:
     // https://tools.ietf.org/html/rfc7232#section-2.3
     const expectedEtag = '"' + clientVersion + '"';
+    const weakEtag = "W/" + expectedEtag;
 
     const etag = req.headers["if-none-match"];
     if (etag) {
-      if (expectedEtag == etag) {
+      if (expectedEtag === etag || weakEtag === etag) {
         debug("serve client %s 304", type);
         res.writeHead(304);
         res.end();
@@ -464,13 +485,13 @@ export class Server extends EventEmitter {
     filename: string,
     req: http.IncomingMessage,
     res: http.ServerResponse
-  ) {
+  ): void {
     const readStream = createReadStream(
       path.join(__dirname, "../client-dist/", filename)
     );
     const encoding = accepts(req).encodings(["br", "gzip", "deflate"]);
 
-    const onError = err => {
+    const onError = (err: NodeJS.ErrnoException | null) => {
       if (err) {
         res.end();
       }
@@ -500,10 +521,10 @@ export class Server extends EventEmitter {
    * Binds socket.io to an engine.io instance.
    *
    * @param {engine.Server} engine engine.io (or compatible) server
-   * @return {Server} self
+   * @return self
    * @public
    */
-  public bind(engine): Server {
+  public bind(engine): this {
     this.engine = engine;
     this.engine.on("connection", this.onconnection.bind(this));
     return this;
@@ -513,12 +534,16 @@ export class Server extends EventEmitter {
    * Called with each incoming transport connection.
    *
    * @param {engine.Socket} conn
-   * @return {Server} self
+   * @return self
    * @private
    */
-  private onconnection(conn): Server {
+  private onconnection(conn): this {
     debug("incoming connection with id %s", conn.id);
-    new Client(this, conn);
+    const client = new Client(this, conn);
+    if (conn.protocol === 3) {
+      // @ts-ignore
+      client.connect("/");
+    }
     return this;
   }
 
@@ -526,20 +551,13 @@ export class Server extends EventEmitter {
    * Looks up a namespace.
    *
    * @param {String|RegExp|Function} name nsp name
-   * @param {Function} [fn] optional, nsp `connection` ev handler
+   * @param fn optional, nsp `connection` ev handler
    * @public
    */
   public of(
-    name:
-      | string
-      | RegExp
-      | ((
-          name: string,
-          query: object,
-          fn: (err: Error, success: boolean) => void
-        ) => void),
+    name: string | RegExp | ParentNspNameMatchFn,
     fn?: (socket: Socket) => void
-  ) {
+  ): Namespace {
     if (typeof name === "function" || name instanceof RegExp) {
       const parentNsp = new ParentNamespace(this);
       debug("initializing parent namespace %s", parentNsp.name);
@@ -573,7 +591,7 @@ export class Server extends EventEmitter {
   /**
    * Closes server connection
    *
-   * @param {Function} [fn] optional, called as `fn([err])` on error OR all conns closed
+   * @param [fn] optional, called as `fn([err])` on error OR all conns closed
    * @public
    */
   public close(fn?: (err?: Error) => void): void {
@@ -593,12 +611,12 @@ export class Server extends EventEmitter {
   /**
    * Sets up namespace middleware.
    *
-   * @return {Server} self
+   * @return self
    * @public
    */
   public use(
     fn: (socket: Socket, next: (err?: ExtendedError) => void) => void
-  ): Server {
+  ): this {
     this.sockets.use(fn);
     return this;
   }
@@ -606,11 +624,11 @@ export class Server extends EventEmitter {
   /**
    * Targets a room when emitting.
    *
-   * @param {String} name
-   * @return {Server} self
+   * @param name
+   * @return self
    * @public
    */
-  public to(name: Room): Server {
+  public to(name: Room): this {
     this.sockets.to(name);
     return this;
   }
@@ -618,11 +636,11 @@ export class Server extends EventEmitter {
   /**
    * Targets a room when emitting.
    *
-   * @param {String} name
-   * @return {Server} self
+   * @param name
+   * @return self
    * @public
    */
-  public in(name: Room): Server {
+  public in(name: Room): this {
     this.sockets.in(name);
     return this;
   }
@@ -630,24 +648,22 @@ export class Server extends EventEmitter {
   /**
    * Sends a `message` event to all clients.
    *
-   * @return {Server} self
+   * @return self
    * @public
    */
-  public send(...args): Server {
-    args.unshift("message");
-    this.sockets.emit.apply(this.sockets, args);
+  public send(...args: readonly any[]): this {
+    this.sockets.emit("message", ...args);
     return this;
   }
 
   /**
    * Sends a `message` event to all clients.
    *
-   * @return {Server} self
+   * @return self
    * @public
    */
-  public write(...args): Server {
-    args.unshift("message");
-    this.sockets.emit.apply(this.sockets, args);
+  public write(...args: readonly any[]): this {
+    this.sockets.emit("message", ...args);
     return this;
   }
 
@@ -663,11 +679,11 @@ export class Server extends EventEmitter {
   /**
    * Sets the compress flag.
    *
-   * @param {Boolean} compress - if `true`, compresses the sending data
-   * @return {Server} self
+   * @param compress - if `true`, compresses the sending data
+   * @return self
    * @public
    */
-  public compress(compress: boolean): Server {
+  public compress(compress: boolean): this {
     this.sockets.compress(compress);
     return this;
   }
@@ -677,10 +693,10 @@ export class Server extends EventEmitter {
    * 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 {Server} self
+   * @return self
    * @public
    */
-  public get volatile(): Server {
+  public get volatile(): this {
     this.sockets.volatile;
     return this;
   }
@@ -688,10 +704,10 @@ export class Server extends EventEmitter {
   /**
    * Sets a modifier for a subsequent event emission that the event data will only be broadcast to the current node.
    *
-   * @return {Server} self
+   * @return self
    * @public
    */
-  public get local(): Server {
+  public get local(): this {
     this.sockets.local;
     return this;
   }
@@ -701,14 +717,14 @@ export class Server extends EventEmitter {
  * Expose main namespace (/).
  */
 
-const emitterMethods = Object.keys(EventEmitter.prototype).filter(function(
+const emitterMethods = Object.keys(EventEmitter.prototype).filter(function (
   key
 ) {
   return typeof EventEmitter.prototype[key] === "function";
 });
 
-emitterMethods.forEach(function(fn) {
-  Server.prototype[fn] = function() {
+emitterMethods.forEach(function (fn) {
+  Server.prototype[fn] = function () {
     return this.sockets[fn].apply(this.sockets, arguments);
   };
 });

lib/namespace.ts

@@ -1,10 +1,10 @@
 import { Socket, RESERVED_EVENTS } from "./socket";
-import { Server } from "./index";
-import { Client } from "./client";
+import type { Server } from "./index";
+import type { Client } from "./client";
 import { EventEmitter } from "events";
 import { PacketType } from "socket.io-parser";
 import debugModule from "debug";
-import { Adapter, Room, SocketId } from "socket.io-adapter";
+import type { Adapter, Room, SocketId } from "socket.io-adapter";
 
 const debug = debugModule("socket.io:namespace");
 
@@ -23,7 +23,7 @@ export class Namespace extends EventEmitter {
 
   /** @private */
   _fns: Array<
-    (socket: Socket, next: (err: ExtendedError) => void) => void
+    (socket: Socket, next: (err?: ExtendedError) => void) => void
   > = [];
 
   /** @private */
@@ -38,8 +38,8 @@ export class Namespace extends EventEmitter {
   /**
    * Namespace constructor.
    *
-   * @param {Server} server instance
-   * @param {string} name
+   * @param server instance
+   * @param name
    */
   constructor(server: Server, name: string) {
     super();
@@ -56,18 +56,18 @@ export class Namespace extends EventEmitter {
    * @private
    */
   _initAdapter(): void {
-    this.adapter = new (this.server.adapter())(this);
+    this.adapter = new (this.server.adapter()!)(this);
   }
 
   /**
    * Sets up namespace middleware.
    *
-   * @return {Namespace} self
+   * @return self
    * @public
    */
   public use(
     fn: (socket: Socket, next: (err?: ExtendedError) => void) => void
-  ): Namespace {
+  ): this {
     this._fns.push(fn);
     return this;
   }
@@ -75,16 +75,16 @@ export class Namespace extends EventEmitter {
   /**
    * Executes the middleware for an incoming client.
    *
-   * @param {Socket} socket - the socket that will get added
-   * @param {Function} fn - last fn call in the middleware
+   * @param socket - the socket that will get added
+   * @param fn - last fn call in the middleware
    * @private
    */
-  private run(socket: Socket, fn: (err: ExtendedError) => void) {
+  private run(socket: Socket, fn: (err: ExtendedError | null) => void) {
     const fns = this._fns.slice(0);
     if (!fns.length) return fn(null);
 
-    function run(i) {
-      fns[i](socket, function(err) {
+    function run(i: number) {
+      fns[i](socket, function (err) {
         // upon error, short-circuit
         if (err) return fn(err);
 
@@ -102,11 +102,11 @@ export class Namespace extends EventEmitter {
   /**
    * Targets a room when emitting.
    *
-   * @param {String} name
-   * @return {Namespace} self
+   * @param name
+   * @return self
    * @public
    */
-  public to(name: Room): Namespace {
+  public to(name: Room): this {
     this._rooms.add(name);
     return this;
   }
@@ -114,11 +114,11 @@ export class Namespace extends EventEmitter {
   /**
    * Targets a room when emitting.
    *
-   * @param {String} name
-   * @return {Namespace} self
+   * @param name
+   * @return self
    * @public
    */
-  public in(name: Room): Namespace {
+  public in(name: Room): this {
     this._rooms.add(name);
     return this;
   }
@@ -132,14 +132,19 @@ export class Namespace extends EventEmitter {
   _add(client: Client, query, fn?: () => void): Socket {
     debug("adding socket to nsp %s", this.name);
     const socket = new Socket(this, client, query);
-    this.run(socket, err => {
+    this.run(socket, (err) => {
       process.nextTick(() => {
         if ("open" == client.conn.readyState) {
-          if (err)
-            return socket._error({
-              message: err.message,
-              data: err.data
-            });
+          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);
@@ -178,10 +183,10 @@ export class Namespace extends EventEmitter {
   /**
    * Emits to all clients.
    *
-   * @return {Boolean} Always true
+   * @return Always true
    * @public
    */
-  public emit(ev: string, ...args: any[]): boolean {
+  public emit(ev: string | Symbol, ...args: any[]): true {
     if (RESERVED_EVENTS.has(ev)) {
       throw new Error(`"${ev}" is a reserved event name`);
     }
@@ -189,7 +194,7 @@ export class Namespace extends EventEmitter {
     args.unshift(ev);
     const packet = {
       type: PacketType.EVENT,
-      data: args
+      data: args,
     };
 
     if ("function" == typeof args[args.length - 1]) {
@@ -205,7 +210,7 @@ export class Namespace extends EventEmitter {
 
     this.adapter.broadcast(packet, {
       rooms: rooms,
-      flags: flags
+      flags: flags,
     });
 
     return true;
@@ -214,31 +219,29 @@ export class Namespace extends EventEmitter {
   /**
    * Sends a `message` event to all clients.
    *
-   * @return {Namespace} self
+   * @return self
    * @public
    */
-  public send(...args): Namespace {
-    args.unshift("message");
-    this.emit.apply(this, args);
+  public send(...args: readonly any[]): this {
+    this.emit("message", ...args);
     return this;
   }
 
   /**
    * Sends a `message` event to all clients.
    *
-   * @return {Namespace} self
+   * @return self
    * @public
    */
-  public write(...args): Namespace {
-    args.unshift("message");
-    this.emit.apply(this, args);
+  public write(...args: readonly any[]): this {
+    this.emit("message", ...args);
     return this;
   }
 
   /**
    * Gets a list of clients.
    *
-   * @return {Namespace} self
+   * @return self
    * @public
    */
   public allSockets(): Promise<Set<SocketId>> {
@@ -255,11 +258,11 @@ export class Namespace extends EventEmitter {
   /**
    * Sets the compress flag.
    *
-   * @param {Boolean} compress - if `true`, compresses the sending data
-   * @return {Namespace} self
+   * @param compress - if `true`, compresses the sending data
+   * @return self
    * @public
    */
-  public compress(compress: boolean): Namespace {
+  public compress(compress: boolean): this {
     this._flags.compress = compress;
     return this;
   }
@@ -269,10 +272,10 @@ export class Namespace extends EventEmitter {
    * 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 {Namespace} self
+   * @return self
    * @public
    */
-  public get volatile(): Namespace {
+  public get volatile(): this {
     this._flags.volatile = true;
     return this;
   }
@@ -280,10 +283,10 @@ export class Namespace extends EventEmitter {
   /**
    * Sets a modifier for a subsequent event emission that the event data will only be broadcast to the current node.
    *
-   * @return {Namespace} self
+   * @return self
    * @public
    */
-  public get local(): Namespace {
+  public get local(): this {
     this._flags.local = true;
     return this;
   }

lib/parent-namespace.ts

@@ -1,20 +1,26 @@
 import { Namespace } from "./namespace";
+import type { Server } from "./index";
 
 export class ParentNamespace extends Namespace {
   private static count: number = 0;
   private children: Set<Namespace> = new Set();
 
-  constructor(server) {
+  constructor(server: Server) {
     super(server, "/_" + ParentNamespace.count++);
   }
 
-  _initAdapter() {}
+  /**
+   * @private
+   */
+  _initAdapter(): void {
+    /* no-op */
+  }
 
-  public emit(...args: any[]): boolean {
-    this.children.forEach(nsp => {
+  public emit(ev: string | Symbol, ...args: [...any]): true {
+    this.children.forEach((nsp) => {
       nsp._rooms = this._rooms;
       nsp._flags = this._flags;
-      nsp.emit.apply(nsp, args);
+      nsp.emit(ev, ...args);
     });
     this._rooms.clear();
     this._flags = {};
@@ -22,16 +28,14 @@ export class ParentNamespace extends Namespace {
     return true;
   }
 
-  createChild(name) {
+  createChild(name: string): Namespace {
     const namespace = new Namespace(this.server, name);
     namespace._fns = this._fns.slice(0);
-    this.listeners("connect").forEach(listener =>
-      // @ts-ignore
-      namespace.on("connect", listener)
+    this.listeners("connect").forEach((listener) =>
+      namespace.on("connect", listener as (...args: any[]) => void)
     );
-    this.listeners("connection").forEach(listener =>
-      // @ts-ignore
-      namespace.on("connection", listener)
+    this.listeners("connection").forEach((listener) =>
+      namespace.on("connection", listener as (...args: any[]) => void)
     );
     this.children.add(namespace);
     this.server._nsps.set(name, namespace);