Pusher Javascript library
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Pusher Javascript Client

This library is an open source client that allows Javascript clients to connect to the Pusher webservice. It is highly recommended that you use the hosted version of this file to stay up to date with the latest updates.

We have included with this library the source code for the websocket-js library with it own licensing.

Usage overview

The following topics are covered:

  • Configuration
  • Connection
  • Socket ids
  • Subscribing to channels (public and private)
  • Binding to events
    • Globally
    • Per-channel
  • Default events


There are a number of variables which can be set for the Pusher client. For most users, there is little need to change these.


This can be changed to point to alternative Pusher URLs (used internally for our staging server).


Endpoint on your server that will return the authentication signature needed for private channels.


A websocket (or Flash Fallback) connection is established by providing your API key to the constructor function:

var socket = new Pusher(API_KEY);

This returns a socket object which can then be used to subscribe to channels. A channel name, or selection of channel names can be supplied at this point for auto-subscription:

var socket = new Pusher(API_KEY, channel_name);

Socket IDs

Making a connection provides the client with a new socket_id that is assigned by the server. This can be used to distinguish the client's own events. A change of state might otherwise be duplicated in the client. More information on this pattern is available here.

It is also stored within the socket, and used as a token for generating signatures for private channels.

Subscribing to channels

Public channels

The default method for subscribing to a channel involves invoking the subscribe method of your socket object:

var my_channel = socket.subscribe('my-channel');

This returns a Channel object which events can be bound to.

Private channels

Private channels are created in exactly the same way as normal channels, except that they reside in the 'private-' namespace. This means prefixing the channel name:

var my_channel = socket.subscribe('private-my-channel');

It is possible to access channels by name, through the channel function:

channel = socket.channel('private-my-channel');

Binding to events

Events can be bound to at 2 levels, the global, and per channel. They take a very similar form to the way events are handled in jQuery.

Global events

You can attach behaviour to these events regardless of the channel the event is broadcast to. The following is an example of an app that binds to new comments from any channel:

var socket = new Pusher('MY_API_KEY', 'my-channel');
  function(data) {
    // add comment into page

Per-channel events

These are bound to a specific channel, and mean that you can reuse event names in different parts of you client application. The following might be an example of a stock tracking app where several channels are opened for different companies:

var socket = new Pusher('MY_API_KEY');
var channel = socket.subscribe('APPL');
  function(data) {
    // add new price into the APPL widget

Binding to everything

It is possible to bind to all events at either the global or channel level by using the method bind_all. This is used for debugging, but may have other utilities.

Default events

There are a number of events which are used internally, but can also be of use elsewhere:

  • connection_established
  • subscribe


Use Bundler to install all development dependencies

bundle install

and create a local config file

mv config/config.yml.example config/config.yml # and edit

Run a development server which serves bundled javascript from http://localhost:5555/pusher.js so that you can edit files in /src freely.

bundle exec jbundle server

In order to build the minified versions:

ENVIRONMENT=development rake build

If you wish to host the javascript on your own server you need to change [:js][:host] in config.yml and then rebuild.


./JFile declares all bundles, src dir and target dir. See https://github.com/ismasan/jbundle Define the version number in JFile (should be in the format 1.2.3).

rake build

That writes source and minified versions of each bundle declared in the JFile into versioned directories. For example if the JFile says

version '1.7.1'

Then rake build will put copies of the files in ./dist/1.7.1/ and ./dist/1.7/

However for a prerelease

version '1.7.2-pre'

It will only write to the full, suffixed directory ./dist/1.7.2-pre

This is so prereleases don't overwrite the previous stable release.


To run the tests first start the testing server by running rake test then visit http://localhost:4567/. The server posts to the production Pusher API using the environment variable PUSHER_URL in the form of:


The tests link to a development version of the combined Pusher Javascript file http://localhost:4567/pusher.js allowing you to modify files in src.