This commit fixes several issues with emit types:
- calling `emit()` without calling `timeout()` first is now only available for events without acknowledgement
- calling `emit()` after calling `timeout()` is now only available for events with an acknowledgement
- calling `emitWithAck()` is now only available for events with an acknowledgement
- `timeout()` must be called before calling `emitWithAck()`
Wrapping SocketData with Partial causes issues when reading data even
if you've made sure to pass all values. If someone want to make their
type Partial or make only a few properties optional, they can do so in
their own type instead.
Related: https://github.com/socketio/socket.io/issues/4537
We should reduce the scope of the "event" error in the next major
version, as it is overloaded today:
- it can be sent by the client (`socket.emit("error")`, which is a perfectly valid event name)
- it can be emitted when the connection encounters an error (an invalid packet for example)
- it can be emitted when a packet is rejected in a middleware (`socket.use()`)
Related: https://github.com/socketio/socket.io/issues/2047
This is a follow-up commit of [1]. Without it, adapter.persistSession()
would be called even if the connection state recovery feature was
disabled.
[1]: 54d5ee05a6
This reverts commit 4e64123862.
Using the id of the socket is not possible, since it is lost upon
reconnection (unless connection recovery is successful), so we revert
the previous change.
This commit adds some syntactic sugar around acknowledgements:
- `emitWithAck()`
```js
try {
const responses = await io.timeout(1000).emitWithAck("some-event");
console.log(responses); // one response per client
} catch (e) {
// some clients did not acknowledge the event in the given delay
}
io.on("connection", async (socket) => {
// without timeout
const response = await socket.emitWithAck("hello", "world");
// with a specific timeout
try {
const response = await socket.timeout(1000).emitWithAck("hello", "world");
} catch (err) {
// the client did not acknowledge the event in the given delay
}
});
```
- `serverSideEmitWithAck()`
```js
try {
const responses = await io.timeout(1000).serverSideEmitWithAck("some-event");
console.log(responses); // one response per server (except itself)
} catch (e) {
// some servers did not acknowledge the event in the given delay
}
```
Related:
- https://github.com/socketio/socket.io/issues/4175
- https://github.com/socketio/socket.io/issues/4577
- https://github.com/socketio/socket.io/issues/4583
Connection state recovery allows a client to reconnect after a
temporary disconnection and restore its state:
- id
- rooms
- data
- missed packets
Usage:
```js
import { Server } from "socket.io";
const io = new Server({
connectionStateRecovery: {
// default values
maxDisconnectionDuration: 2 * 60 * 1000,
skipMiddlewares: true,
},
});
io.on("connection", (socket) => {
console.log(socket.recovered); // whether the state was recovered or not
});
```
Here's how it works:
- the server sends a session ID during the handshake (which is
different from the current `id` attribute, which is public and can be
freely shared)
- the server also includes an offset in each packet (added at the end
of the data array, for backward compatibility)
- upon temporary disconnection, the server stores the client state for
a given delay (implemented at the adapter level)
- upon reconnection, the client sends both the session ID and the last
offset it has processed, and the server tries to restore the state
A few notes:
- the base adapter exposes two additional methods, persistSession() and
restoreSession(), that must be implemented by the other adapters in
order to allow the feature to work within a cluster
See: f5294126a8
- acknowledgements are not affected, because it won't work if the
client reconnects on another server (as the ack id is local)
- any disconnection that lasts longer than the
`maxDisconnectionDuration` value will result in a new session, so users
will still need to care for the state reconciliation between the server
and the client
Related: https://github.com/socketio/socket.io/discussions/4510
Note: some disconnection reasons could be merged in the next major
release, i.e. the Deno impl does not have "forced server close" and
"server shutting down"
Related: https://github.com/socketio/socket.io/issues/4387
This commit handles several edge cases that were silently ignored
before:
- receiving several CONNECT packets during a session
- receiving any packet without CONNECT packet first
Syntax:
```js
io.timeout(1000).emit("some-event", (err, responses) => {
// ...
});
```
The adapter exposes two additional methods:
- `broadcastWithAck(packets, opts, clientCountCallback, ack)`
Similar to `broadcast(packets, opts)`, but:
* `clientCountCallback()` is called with the number of clients that
received the packet (can be called several times in a cluster)
* `ack()` is called for each client response
- `serverCount()`
It returns the number of Socket.IO servers in the cluster (1 for the
in-memory adapter).
Those two methods will be implemented in the other adapters (Redis,
Postgres, MongoDB, ...).
Related:
- https://github.com/socketio/socket.io/issues/1811
- https://github.com/socketio/socket.io/issues/4163
- https://github.com/socketio/socket.io-redis-adapter/issues/445
So that it can be used by the end users:
```ts
const myMiddleware = ([eventName, ...args]: Event, next: (err?: Error) => void) => {
console.log(eventName); // inferred as string
next();
}
io.on("connection", (socket) => {
socket.use(myMiddleware);
});
```
The Socket instance is only considered connected when the "connection"
event is emitted, and not during the middleware(s) execution.
```js
io.use((socket, next) => {
console.log(socket.connected); // prints "false"
next();
});
io.on("connection", (socket) => {
console.log(socket.connected); // prints "true"
});
```
Related: https://github.com/socketio/socket.io/issues/4129
Syntax:
```js
// server A
io.serverSideEmit("hello", "world");
// server B
io.on("hello", (arg) => {
console.log(arg); // prints "world"
});
```
With acknowledgements:
```js
// server A
io.serverSideEmit("hello", "world", (err, responses) => {
console.log(responses); // prints ["hi"]
});
// server B
io.on("hello", (arg, callback) => {
callback("hi");
});
```
This feature replaces the customHook/customRequest API from the Redis
adapter: https://github.com/socketio/socket.io-redis/issues/370
Syntax:
```ts
interface ClientToServerEvents {
"my-event": (a: number, b: string, c: number[]) => void;
}
interface ServerToClientEvents {
hello: (message: string) => void;
}
const io = new Server<ClientToServerEvents, ServerToClientEvents>(httpServer);
io.emit("hello", "world");
io.on("connection", (socket) => {
socket.on("my-event", (a, b, c) => {
// ...
});
socket.emit("hello", "again");
});
```
The events are not typed by default (inferred as any), so this change
is backward compatible.
Note: we could also have reused the method here ([1]) to add types to
the EventEmitter, instead of creating a StrictEventEmitter class.
Related: https://github.com/socketio/socket.io/issues/3742
[1]: https://github.com/binier/tiny-typed-emitter
This commit adds the following methods:
- fetchSockets: returns the matching socket instances
Syntax:
```js
// return all Socket instances
const sockets = await io.fetchSockets();
// return all Socket instances of the "admin" namespace in the "room1" room
const sockets = await io.of("/admin").in("room1").fetchSockets();
```
- socketsJoin: makes the matching socket instances join the specified rooms
Syntax:
```js
// make all Socket instances join the "room1" room
io.socketsJoin("room1");
// make all Socket instances of the "admin" namespace in the "room1" room join the "room2" room
io.of("/admin").in("room1").socketsJoin("room2");
```
- socketsLeave: makes the matching socket instances leave the specified rooms
Syntax:
```js
// make all Socket instances leave the "room1" room
io.socketsLeave("room1");
// make all Socket instances of the "admin" namespace in the "room1" room leave the "room2" room
io.of("/admin").in("room1").socketsLeave("room2");
```
- disconnectSockets: makes the matching socket instances disconnect
Syntax:
```js
// make all Socket instances disconnect
io.disconnectSockets();
// make all Socket instances of the "admin" namespace in the "room1" room disconnect
io.of("/admin").in("room1").disconnectSockets();
```
Those methods share the same semantics as broadcasting. They will also
work with multiple Socket.IO servers when using the Redis adapter. In
that case, the fetchSockets() method will return a list of RemoteSocket
instances, which expose a subset of the methods and attributes of the
Socket class (the "request" attribute cannot be mocked, for example).
Related:
- https://github.com/socketio/socket.io/issues/3042
- https://github.com/socketio/socket.io/issues/3418
- https://github.com/socketio/socket.io/issues/3570
- https://github.com/socketio/socket.io-redis/issues/283
In some cases it is necessary to pass an array of rooms instead of a single room.
New syntax:
```
io.to(["room1", "room2"]).except(["room3"]).emit(...);
socket.to(["room1", "room2"]).except(["room3"]).emit(...);
```
Related: https://github.com/socketio/socket.io/issues/3048
Previously, broadcasting to a given room (by calling `io.to()`) would
mutate the io instance, which could lead to surprising behaviors, like:
```js
io.to("room1");
io.to("room2").emit(...); // also sent to room1
// or with async/await
io.to("room3").emit("details", await fetchDetails()); // random behavior: maybe in room3, maybe to all clients
```
Calling `io.to()` (or any other broadcast modifier) will now return an
immutable instance.
Related:
- https://github.com/socketio/socket.io/issues/3431
- https://github.com/socketio/socket.io/issues/3444
In order to ease the migration to Socket.IO v3, the Socket.IO server
can now communicate with v2 clients.
```js
const io = require("socket.io")({
allowEIO3: true
});
```
This feature is disabled by default.
This functionality was removed in [1] (included in 3.0.0), but
catch-all listeners and socket middleware features are complementary
rather than mutually exclusive.
The only difference with the previous implementation is that passing an
error to the `next` handler will create an error on the server-side,
and not on the client-side anymore.
```js
io.on("connection", (socket) => {
socket.use(([ event, ...args ], next) => {
next(new Error("stop"));
});
socket.on("error", (err) => {
// to restore the previous behavior
socket.emit("error", err);
// or close the connection, depending on your use case
socket.disconnect(true);
});
});
```
This creates additional possibilities about custom error handlers, which
may be implemented in the future.
```js
// user-defined error handler
socket.use((err, [ event ], next) => {
// either handle it
socket.disconnect();
// or forward the error to the default error handler
next(err);
});
// default error handler
socket.use((err, _, next) => {
socket.emit("error", err);
});
```
Related: https://github.com/socketio/socket.io/issues/3678
[1]: 5c73733985
The previous signature was not compatible with EventEmitter.emit(). The typescript compilation threw:
```
node_modules/socket.io/dist/namespace.d.ts(89,5): error TS2416: Property 'emit' in type 'Namespace' is not assignable to the same property in base type 'EventEmitter'.
Type '(ev: string, ...args: any[]) => Namespace' is not assignable to type '(event: string | symbol, ...args: any[]) => boolean'.
Type 'Namespace' is not assignable to type 'boolean'.
node_modules/socket.io/dist/socket.d.ts(84,5): error TS2416: Property 'emit' in type 'Socket' is not assignable to the same property in base type 'EventEmitter'.
Type '(ev: string, ...args: any[]) => this' is not assignable to type '(event: string | symbol, ...args: any[]) => boolean'.
Type 'this' is not assignable to type 'boolean'.
Type 'Socket' is not assignable to type 'boolean'.
```
Note: the emit calls cannot be chained anymore:
```js
socket.emit("hello").emit("world"); // will not work anymore
```
Inspired from EventEmitter2 [1]
```js
io.on("connect", socket => {
socket.onAny((event, ...args) => {});
socket.prependAny((event, ...args) => {});
socket.offAny(); // remove all listeners
socket.offAny(listener);
const listeners = socket.listenersAny();
});
```
Breaking change: the socket.use() method is removed
This method was introduced in [2] for the same feature (having a
catch-all listener), but there were two issues:
- the API is not very user-friendly, since the user has to know the structure of the packet argument
- it uses an ERROR packet, which is reserved for Namespace authentication issues (see [3])
[1]: https://github.com/EventEmitter2/EventEmitter2
[2]: https://github.com/socketio/socket.io/issues/434
[3]: https://github.com/socketio/socket.io-protocol
Depending on the adapter, Socket#join() may return:
- nothing (in-memory and Redis adapters)
- a promise (custom adapters)
Breaking change: Socket#join() and Socket#leave() do not accept a
callback argument anymore.
Before:
```js
socket.join("room1", () => {
io.to("room1").emit("hello");
});
```
After:
```
socket.join("room1");
io.to("room1").emit("hello");
// or await socket.join("room1"); for custom adapters
```
Note: the need for an asynchronous method came from the Redis adapter,
which did override the Adapter#add() method in earlier versions, but
this is not the case anymore.
Reference:
- https://github.com/socketio/socket.io/blob/2.3.0/lib/socket.js#L236-L258
- https://github.com/socketio/socket.io-adapter/blob/1.1.2/index.js#L56-L65
- 05f926e13e
Related: https://github.com/socketio/socket.io/issues/3662
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"
