An AngularJS service for interacting with WebSockets.

angular, javascript, websockets
bower install ngSocket


ngSocket Build Status

Status: In-Development

An AngularJS 1.x service for connecting applications to servers with WebSocket support.


bower install ngSocket

.controller('SomeController', function (ngSocket) {
  //Open a WebSocket connection
  var ws = ngSocket('ws://foo/bar');

  //Can call before socket has opened
  ws.send({foo: 'bar'});


Factory: ngSocket (in module ngSocket)

returns instance of NGWebSocket


name arguments description
url:String Creates and opens a WebSocket instance. var ws = ngSocket('ws://foo');
send data:String,Object returns Adds data to a queue, and attempts to send if socket is ready. Accepts string or object, and will stringify objects before sending to socket.
onMessage callback:Function
options{filter:String,RegExp, autoApply:Boolean=true}
Register a callback to be fired on every message received from the websocket, or optionally just when the message's data property matches the filter provided in the options object. Each message handled will safely call $rootScope.$digest() unless autoApply is set to `false in the options. Callback gets called with a MessageEvent object.
onOpen callback:Function Function to be executed each time a socket connection is opened for this instance.
close force:Boolean:optional Close the underlying socket, as long as no data is still being sent from the client. Optionally force close, even if data is still being sent, by passing true as the force parameter. To check if data is being sent, read the value of socket.bufferedAmount.


name type description
socket window.WebSocket WebSocket instance.
sendQueue Array Queue of send calls to be made on socket when socket is able to receive data. List is populated by calls to the send method, but this array can be spliced if data needs to be manually removed before it's been sent to a socket. Data is removed from the array after it's been sent to the socket.
onOpenCallbacks Array List of callbacks to be executed when the socket is opened, initially or on re-connection after broken connection. Callbacks should be added to this list through the onOpen method.
onMessageCallbacks Array List of callbacks to be executed when a message is received from the socket. Callbacks should be added via the onMessage method.
readyState Number:readonly Returns either the readyState value from the underlying WebSocket instance, or a proprietary value representing the internal state of the lib, e.g. if the lib is in a state of re-connecting.


This type is returned from the send() instance method of ngSocket, inherits from $q.defer().promise.


name arguments description
cancel Alias to deferred.reject(), allows preventing an unsent message from being sent to socket for any arbitrary reason.
then resolve:Function, reject:Function Resolves when message has been passed to socket, presuming the socket has a readyState of 1. Rejects if the socket is hopelessly disconnected now or in the future (i.e. the library is no longer attempting to reconnect). All messages are immediately rejected when the library has determined that re-establishing a connection is unlikely.

Service: ngSocketBackend (in module ngSocketMock)

Similar to httpBackend mock in AngularJS's ngMock module


name arguments description
flush Executes all pending requests
expectConnect url:String Specify the url of an expected WebSocket connection
expectClose Expect "close" to be called on the WebSocket
expectSend msg:String Expectation of send to be called, with required message
verifyNoOutstandingExpectation Makes sure all expectations have been satisfied, should be called in afterEach
verifyNoOutstandingRequest Makes sure no requests are pending, should be called in afterEach

Logical Questions

  • Q.: What if the browser doesn't support WebSockets?
  • A.: This module will not help; it does not have a fallback story for browsers that do not support WebSockets.


$ npm install
$ bower install

Unit Tests

$ npm test Starts karma and watches files for changes

Manual Tests

In the project root directory:

$ node test-server Starts a sample web socket server to send/receive messages $ ./node_modules/.bin http-server - Basic http server to seve a static file Open localhost:8081/test-app.html and watch browser console and node console to see messages passing


$ ./ For now just copies src/ngSocket.js to dist/ (bower is configured to ignore src/ and test, plus pretty much everything else)


  • Automatic re-connection when connection lost
  • Add onerror to allow applications to respond to socket errors in their own ways
  • Consider support for ArrayBuffer and Blob datatypes
  • Add protocols parameter to constructor


Apache 2.0