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