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
This commit adds a new option, "cleanupEmptyChildNamespaces". With this
option enabled (disabled by default), when a socket disconnects from a
dynamic namespace and if there are no other sockets connected to it
then the namespace will be cleaned up and its adapter will be closed.
Note: the namespace can be connected to later (it will be recreated)
Related: https://github.com/socketio/socket.io-redis-adapter/issues/480
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
This adds typings for the socket.io engine field, which offers better
IntelliSense when retrieving the server, as well as more confidence on
the developer-side of what types of fields are entering the server.
Related: https://github.com/socketio/socket.io/issues/4590
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);
});
```
Using an async operation with `io.use()` could lead to the creation of
several instances of a same namespace, each of them overriding the
previous one.
Example:
```js
io.use(async (nsp, auth, next) => {
await anOperationThatTakesSomeTime();
next();
});
```
Related: https://github.com/socketio/socket.io/pull/4136
This header is useless, as the client bundle already contains a
sourceMappingURL field.
Besides, Firefox prints the following warning:
> <url> is being assigned a //# sourceMappingURL, but already has one
Related: https://github.com/socketio/socket.io/issues/3958
A "new_namespace" event will be emitted when a new namespace is created:
```js
io.on("new_namespace", (namespace) => {
// ...
});
```
This could be used for example for registering the same middleware for
each namespace.
See https://github.com/socketio/socket.io/issues/3851
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
Before this change, `require("socket.io").Socket` would return
"undefined".
Note: having access to the Socket class allows users to modify its
prototype.
Related: https://github.com/socketio/socket.io/issues/3726
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
When handling compression at the proxy server level, the client receives a weak ETag.
Weak ETags are prefixed with `W/`, e.g. `W/"2.2.0"`.
Upon cache validation we should take care of these too.
Reference: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/ETag
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.
So that the following example:
```js
const io = require('socket.io')({
pingTimeout: 10000
});
io.listen(3000);
```
behaves the same as:
```js
const io = require('socket.io')(3000, {
pingTimeout: 10000
});
```
Before this change, the options in the first example were not forwarded
to the Engine.IO constructor, which is not really intuitive.
The previous syntax (which is still valid):
```js
const io = require('socket.io')();
io.listen(3000, {
pingTimeout: 10000
});
```
