Both the "connected" and the "_sockets" maps were used to track the
Socket instances in the namespace.
Let's merge them into "sockets". It's a breaking change, but:
- the "sockets" object did already exist in Socket.IO v2 (and appears in some examples/tutorials)
- "sockets" makes more sense than "connected" in my opinion
- there was already a breaking change regarding the "connected" property (from object to Map)
Breaking change: the "connected" map is renamed to "sockets"
Both CommonJS and ES6 import are now supported:
- with `{ "type": "commonjs" }` in the package.json file
```js
const io = require("socket.io")(8080);
// or
const { Server } = require("socket.io");
const io = new Server(8080);
```
- with `{ "type": "module" }`
```js
import { Server } from "socket.io";
const io = new Server(8080);
```
Related: https://nodejs.org/api/packages.html#packages_dual_commonjs_es_module_packages
In previous versions, the Socket#id attribute was equal (or derived,
for a non-default namespace) to the underlying Engine.IO id, which is
used as a mean to authenticate the user throughout the Engine.IO
session and thus is sensitive information that should be kept secret.
The problem with reusing the Engine.IO id is that users could be
tempted to transmit this id to other clients, in order to implement
private messaging for example.
So we'll now generate a new random id for each new socket.
Please note that this id will now be different from the one found in
the query parameters of the HTTP requests.
In previous versions, a client was always connected to the default
namespace, even if it requested access to another namespace.
This meant that the middlewares registered for the default namespace
were triggered in any case, which is a surprising behavior for end
users.
This also meant that the query option of the Socket on the client-side
was not sent in the Socket.IO CONNECT packet for the default namespace:
```js
// default namespace: query sent in the query params
const socket = io({
query: {
abc: "def"
}
});
// another namespace: query sent in the query params + the CONNECT packet
const socket = io("/admin", {
query: {
abc: "def"
}
});
```
The client will now send a CONNECT packet in any case, and the query
option of the Socket is renamed to "auth", in order to make a clear
distinction with the query option of the Manager (included in the query
parameters of the HTTP requests).
```js
// server-side
io.use((socket, next) => {
// not triggered anymore
});
io.of("/admin").use((socket, next => {
// triggered
console.log(socket.handshake.query.abc); // "def"
console.log(socket.handshake.auth.abc); // "123"
});
// client-side
const socket = io("/admin", {
query: {
abc: "def"
},
auth: {
abc: "123"
}
});
```
So that the call to the `has-binary` method can be skipped. Usage:
```
// with binary data
socket.binary(true).emit("binary", obj);
// without binary data
socket.binary(false).emit("string", obj);
// call to hasBin
socket.emit("guess", obj);
```
Includes the following (from engine.io changelog):
* [fix] Initialize the WebSocket server in the Server constructor (#476)
* [chore] Bump ws to version 1.1.2 (vulnerability fix) (#480)
