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A small decorator for the JavaScript WebSocket API that automatically reconnects
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Latest commit fd7c819 Apr 6, 2016 @joewalnes Merge pull request #69 from wjt/patch-1
README.md: update URLs for WebSocket spec

README.md

ReconnectingWebSocket

A small JavaScript library that decorates the WebSocket API to provide a WebSocket connection that will automatically reconnect if the connection is dropped.

It is API compatible, so when you have:

var ws = new WebSocket('ws://....');

you can replace with:

var ws = new ReconnectingWebSocket('ws://....');

Minified library with gzip compression is less than 600 bytes.

How reconnections occur

With the standard WebSocket API, the events you receive from the WebSocket instance are typically:

onopen
onmessage
onmessage
onmessage
onclose // At this point the WebSocket instance is dead.

With a ReconnectingWebSocket, after an onclose event is called it will automatically attempt to reconnect. In addition, a connection is attempted repeatedly (with a small pause) until it succeeds. So the events you receive may look something more like:

onopen
onmessage
onmessage
onmessage
onclose
// ReconnectingWebSocket attempts to reconnect
onopen
onmessage
onmessage
onmessage
onclose
// ReconnectingWebSocket attempts to reconnect
onopen
onmessage
onmessage
onmessage
onclose

This is all handled automatically for you by the library.

Parameters

var socket = new ReconnectingWebSocket(url, protocols, options);

url

protocols

options

  • Options (see below)

Options

Options can either be passed as the 3rd parameter upon instantiation or set directly on the object after instantiation:

var socket = new ReconnectingWebSocket(url, null, {debug: true, reconnectInterval: 3000});

or

var socket = new ReconnectingWebSocket(url);
socket.debug = true;
socket.timeoutInterval = 5400;

debug

  • Whether this instance should log debug messages or not. Debug messages are printed to console.debug().
  • Accepts true or false
  • Default value: false

automaticOpen

  • Whether or not the websocket should attempt to connect immediately upon instantiation. The socket can be manually opened or closed at any time using ws.open() and ws.close().
  • Accepts true or false
  • Default value: true

reconnectInterval

  • The number of milliseconds to delay before attempting to reconnect.
  • Accepts integer
  • Default: 1000

maxReconnectInterval

  • The maximum number of milliseconds to delay a reconnection attempt.
  • Accepts integer
  • Default: 30000

reconnectDecay

  • The rate of increase of the reconnect delay. Allows reconnect attempts to back off when problems persist.
  • Accepts integer or float
  • Default: 1.5

timeoutInterval

  • The maximum time in milliseconds to wait for a connection to succeed before closing and retrying.
  • Accepts integer
  • Default: 2000

maxReconnectAttempts

  • The maximum number of reconnection attempts that will be made before giving up. If null, reconnection attempts will be continue to be made forever.
  • Accepts integer or null.
  • Default: null

binaryType

  • The binary type is required by some applications.
  • Accepts strings 'blob' or 'arraybuffer'.
  • Default: 'blob'

Methods

ws.open()

  • Open the Reconnecting Websocket

ws.close(code, reason)

ws.refresh()

  • Refresh the connection if still open (close and then re-open it).

ws.send(data)

  • Transmits data to the server over the WebSocket connection.
  • Accepts @param data a text string, ArrayBuffer or Blob

Like this? Check out websocketd for the simplest way to create WebSocket backends from any programming language.

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