425 lines
12 KiB
Markdown
425 lines
12 KiB
Markdown
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# socket.io
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[](https://travis-ci.org/socketio/socket.io)
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[](http://slack.socket.io)
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## How to use
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The following example attaches socket.io to a plain Node.JS
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HTTP server listening on port `3000`.
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```js
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var server = require('http').createServer();
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var io = require('socket.io')(server);
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io.on('connection', function(socket){
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socket.on('event', function(data){});
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socket.on('disconnect', function(){});
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});
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server.listen(3000);
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```
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### Standalone
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```js
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var io = require('socket.io')();
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io.on('connection', function(socket){});
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io.listen(3000);
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```
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### In conjunction with Express
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Starting with **3.0**, express applications have become request handler
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functions that you pass to `http` or `http` `Server` instances. You need
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to pass the `Server` to `socket.io`, and not the express application
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function.
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```js
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var app = require('express')();
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var server = require('http').createServer(app);
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var io = require('socket.io')(server);
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io.on('connection', function(){ /* … */ });
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server.listen(3000);
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```
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### In conjunction with Koa
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Like Express.JS, Koa works by exposing an application as a request
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handler function, but only by calling the `callback` method.
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```js
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var app = require('koa')();
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var server = require('http').createServer(app.callback());
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var io = require('socket.io')(server);
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io.on('connection', function(){ /* … */ });
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server.listen(3000);
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```
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## API
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### Server
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Exposed by `require('socket.io')`.
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### Server()
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Creates a new `Server`. Works with and without `new`:
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```js
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var io = require('socket.io')();
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// or
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var Server = require('socket.io');
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var io = new Server();
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```
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### Server(opts:Object)
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Optionally, the first or second argument (see below) of the `Server`
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constructor can be an options object.
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The following options are supported:
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- `serveClient` sets the value for Server#serveClient()
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- `path` sets the value for Server#path()
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The same options passed to socket.io are always passed to
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the `engine.io` `Server` that gets created. See engine.io
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[options](https://github.com/socketio/engine.io#methods-1)
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as reference.
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### Server(srv:http#Server, opts:Object)
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Creates a new `Server` and attaches it to the given `srv`. Optionally
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`opts` can be passed.
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### Server(port:Number, opts:Object)
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Binds socket.io to a new `http.Server` that listens on `port`.
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### Server#serveClient(v:Boolean):Server
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If `v` is `true` the attached server (see `Server#attach`) will serve
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the client files. Defaults to `true`.
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This method has no effect after `attach` is called.
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```js
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// pass a server and the `serveClient` option
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var io = require('socket.io')(http, { serveClient: false });
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// or pass no server and then you can call the method
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var io = require('socket.io')();
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io.serveClient(false);
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io.attach(http);
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```
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If no arguments are supplied this method returns the current value.
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### Server#path(v:String):Server
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Sets the path `v` under which `engine.io` and the static files will be
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served. Defaults to `/socket.io`.
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If no arguments are supplied this method returns the current value.
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### Server#adapter(v:Adapter):Server
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Sets the adapter `v`. Defaults to an instance of the `Adapter` that
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ships with socket.io which is memory based. See
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[socket.io-adapter](https://github.com/socketio/socket.io-adapter).
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If no arguments are supplied this method returns the current value.
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### Server#origins(v:String):Server
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Sets the allowed origins `v`. Defaults to any origins being allowed.
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If no arguments are supplied this method returns the current value.
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### Server#origins(v:Function):Server
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Sets the allowed origins as dynamic function. Function takes two arguments `origin:String` and `callback(error, success)`, where `success` is a boolean value indicating whether origin is allowed or not.
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__Potential drawbacks__:
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* in some situations, when it is not possible to determine `origin` it may have value of `*`
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* As this function will be executed for every request, it is advised to make this function work as fast as possible
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* If `socket.io` is used together with `Express`, the CORS headers will be affected only for `socket.io` requests. For Express can use [cors](https://github.com/expressjs/cors)
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### Server#sockets:Namespace
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The default (`/`) namespace.
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### Server#attach(srv:http#Server, opts:Object):Server
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Attaches the `Server` to an engine.io instance on `srv` with the
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supplied `opts` (optionally).
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### Server#attach(port:Number, opts:Object):Server
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Attaches the `Server` to an engine.io instance that is bound to `port`
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with the given `opts` (optionally).
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### Server#listen
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Synonym of `Server#attach`.
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### Server#bind(srv:engine#Server):Server
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Advanced use only. Binds the server to a specific engine.io `Server`
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(or compatible API) instance.
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### Server#onconnection(socket:engine#Socket):Server
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Advanced use only. Creates a new `socket.io` client from the incoming
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engine.io (or compatible API) `socket`.
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### Server#of(nsp:String):Namespace
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Initializes and retrieves the given `Namespace` by its pathname
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identifier `nsp`.
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If the namespace was already initialized it returns it right away.
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### Server#emit
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Emits an event to all connected clients. The following two are
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equivalent:
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```js
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var io = require('socket.io')();
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io.sockets.emit('an event sent to all connected clients');
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io.emit('an event sent to all connected clients');
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```
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For other available methods, see `Namespace` below.
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### Server#close
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Closes socket server
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```js
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var Server = require('socket.io');
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var PORT = 3030;
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var server = require('http').Server();
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var io = Server(PORT);
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io.close(); // Close current server
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server.listen(PORT); // PORT is free to use
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io = Server(server);
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```
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### Server#use
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See `Namespace#use` below.
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### Namespace
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Represents a pool of sockets connected under a given scope identified
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by a pathname (eg: `/chat`).
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By default the client always connects to `/`.
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#### Events
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- `connection` / `connect`. Fired upon a connection.
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Parameters:
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- `Socket` the incoming socket.
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### Namespace#name:String
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The namespace identifier property.
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### Namespace#connected:Object<Socket>
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Hash of `Socket` objects that are connected to this namespace indexed
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by `id`.
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### Namespace#clients(fn:Function)
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Gets a list of client IDs connected to this namespace (across all nodes if applicable).
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An example to get all clients in a namespace:
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```js
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var io = require('socket.io')();
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io.of('/chat').clients(function(error, clients){
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if (error) throw error;
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console.log(clients); // => [PZDoMHjiu8PYfRiKAAAF, Anw2LatarvGVVXEIAAAD]
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});
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```
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An example to get all clients in namespace's room:
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```js
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var io = require('socket.io')();
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io.of('/chat').in('general').clients(function(error, clients){
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if (error) throw error;
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console.log(clients); // => [Anw2LatarvGVVXEIAAAD]
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});
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```
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As with broadcasting, the default is all clients from the default namespace ('/'):
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```js
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var io = require('socket.io')();
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io.clients(function(error, clients){
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if (error) throw error;
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console.log(clients); // => [6em3d4TJP8Et9EMNAAAA, G5p55dHhGgUnLUctAAAB]
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});
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```
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### Namespace#use(fn:Function):Namespace
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Registers a middleware, which is a function that gets executed for
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every incoming `Socket` and receives as parameter the socket and a
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function to optionally defer execution to the next registered
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middleware.
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```js
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var io = require('socket.io')();
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io.use(function(socket, next){
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if (socket.request.headers.cookie) return next();
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next(new Error('Authentication error'));
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});
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```
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Errors passed to middleware callbacks are sent as special `error`
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packets to clients.
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### Socket
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A `Socket` is the fundamental class for interacting with browser
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clients. A `Socket` belongs to a certain `Namespace` (by default `/`)
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and uses an underlying `Client` to communicate.
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### Socket#rooms:Array
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A list of strings identifying the rooms this socket is in.
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### Socket#client:Client
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A reference to the underlying `Client` object.
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### Socket#conn:Socket
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A reference to the underlying `Client` transport connection (engine.io
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`Socket` object).
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### Socket#request:Request
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A getter proxy that returns the reference to the `request` that
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originated the underlying engine.io `Client`. Useful for accessing
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request headers such as `Cookie` or `User-Agent`.
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### Socket#id:String
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A unique identifier for the socket session, that comes from the
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underlying `Client`.
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### Socket#emit(name:String[, …]):Socket
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Emits an event to the socket identified by the string `name`. Any
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other parameters can be included.
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All datastructures are supported, including `Buffer`. JavaScript
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functions can't be serialized/deserialized.
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```js
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var io = require('socket.io')();
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io.on('connection', function(socket){
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socket.emit('an event', { some: 'data' });
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});
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```
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### Socket#join(name:String[, fn:Function]):Socket
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Adds the socket to the `room`, and fires optionally a callback `fn`
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with `err` signature (if any).
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The socket is automatically a member of a room identified with its
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session id (see `Socket#id`).
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The mechanics of joining rooms are handled by the `Adapter`
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that has been configured (see `Server#adapter` above), defaulting to
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[socket.io-adapter](https://github.com/socketio/socket.io-adapter).
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### Socket#leave(name:String[, fn:Function]):Socket
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Removes the socket from `room`, and fires optionally a callback `fn`
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with `err` signature (if any).
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**Rooms are left automatically upon disconnection**.
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The mechanics of leaving rooms are handled by the `Adapter`
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that has been configured (see `Server#adapter` above), defaulting to
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[socket.io-adapter](https://github.com/socketio/socket.io-adapter).
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### Socket#to(room:String):Socket
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Sets a modifier for a subsequent event emission that the event will
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only be _broadcasted_ to sockets that have joined the given `room`.
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To emit to multiple rooms, you can call `to` several times.
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```js
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var io = require('socket.io')();
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io.on('connection', function(socket){
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socket.to('others').emit('an event', { some: 'data' });
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});
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```
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### Socket#in(room:String):Socket
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Same as `Socket#to`
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### Socket#compress(v:Boolean):Socket
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Sets a modifier for a subsequent event emission that the event data will
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only be _compressed_ if the value is `true`. Defaults to `true` when you don't call the method.
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```js
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var io = require('socket.io')();
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io.on('connection', function(socket){
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socket.compress(false).emit('an event', { some: 'data' });
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});
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```
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### Client
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The `Client` class represents an incoming transport (engine.io)
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connection. A `Client` can be associated with many multiplexed `Socket`
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that belong to different `Namespace`s.
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### Client#conn
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A reference to the underlying `engine.io` `Socket` connection.
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### Client#request
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A getter proxy that returns the reference to the `request` that
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originated the engine.io connection. Useful for accessing
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request headers such as `Cookie` or `User-Agent`.
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## Debug / logging
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Socket.IO is powered by [debug](https://github.com/visionmedia/debug).
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In order to see all the debug output, run your app with the environment variable
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`DEBUG` including the desired scope.
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To see the output from all of Socket.IO's debugging scopes you can use:
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```
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DEBUG=socket.io* node myapp
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```
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## License
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MIT
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