reconnecting-websocket.js

// MIT License:
//
// Copyright (c) 2010-2012, Joe Walnes
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

/**
 * This behaves like a WebSocket in every way, except if it fails to connect,
 * or it gets disconnected, it will repeatedly poll until it successfully connects
 * again.
 *
 * It is API compatible, so when you have:
 *   ws = new WebSocket('ws://....');
 * you can replace with:
 *   ws = new ReconnectingWebSocket('ws://....');
 *
 * The event stream will typically look like:
 *  onconnecting
 *  onopen
 *  onmessage
 *  onmessage
 *  onclose // lost connection
 *  onconnecting
 *  onopen  // sometime later...
 *  onmessage
 *  onmessage
 *  etc...
 *
 * It is API compatible with the standard WebSocket API, apart from the following members:
 *
 * - `bufferedAmount`
 * - `extensions`
 * - `binaryType`
 *
 * Latest version: https://github.com/joewalnes/reconnecting-websocket/
 * - Joe Walnes
 *
 * Syntax
 * ======
 * var socket = new ReconnectingWebSocket(url, protocols, options);
 *
 * Parameters
 * ==========
 * url - The url you are connecting to.
 * protocols - Optional string or array of protocols.
 * options - See below
 *
 * Options
 * =======
 * Options can either be passed upon instantiation or set after instantiation:
 *
 * var socket = new ReconnectingWebSocket(url, null, { debug: true, reconnectInterval: 4000 });
 *
 * or
 *
 * var socket = new ReconnectingWebSocket(url);
 * socket.debug = true;
 * socket.reconnectInterval = 4000;
 *
 * debug
 * - Whether this instance should log debug messages. Accepts true or false. Default: 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().
 *
 * 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.
 *
 */
(function (global, factory) {
  if (typeof define === 'function' && define.amd) {
      define([], factory);
  } else if (typeof module !== 'undefined' && module.exports){
      module.exports = factory();
  } else {
      global.ReconnectingWebSocket = factory();
  }
})(this, function () {

  if (!('WebSocket' in window)) {
      return;
  }

  function ReconnectingWebSocket(url, protocols, options) {

      // Default settings
      var settings = {

          /** Whether this instance should log debug messages. */
          debug: false,

          /** Whether or not the websocket should attempt to connect immediately upon instantiation. */
          automaticOpen: true,

          /** The number of milliseconds to delay before attempting to reconnect. */
          reconnectInterval: 1000,
          /** The maximum number of milliseconds to delay a reconnection attempt. */
          maxReconnectInterval: 30000,
          /** The rate of increase of the reconnect delay. Allows reconnect attempts to back off when problems persist. */
          reconnectDecay: 1.5,

          /** The maximum time in milliseconds to wait for a connection to succeed before closing and retrying. */
          timeoutInterval: 2000,

          /** The maximum number of reconnection attempts to make. Unlimited if null. */
          maxReconnectAttempts: null,

          /** The binary type, possible values 'blob' or 'arraybuffer', default 'blob'. */
          binaryType: 'blob'
      }
      if (!options) { options = {}; }

      // Overwrite and define settings with options if they exist.
      for (var key in settings) {
          if (typeof options[key] !== 'undefined') {
              this[key] = options[key];
          } else {
              this[key] = settings[key];
          }
      }

      // These should be treated as read-only properties

      /** The URL as resolved by the constructor. This is always an absolute URL. Read only. */
      this.url = url;

      /** The number of attempted reconnects since starting, or the last successful connection. Read only. */
      this.reconnectAttempts = 0;

      /**
       * The current state of the connection.
       * Can be one of: WebSocket.CONNECTING, WebSocket.OPEN, WebSocket.CLOSING, WebSocket.CLOSED
       * Read only.
       */
      this.readyState = WebSocket.CONNECTING;

      /**
       * A string indicating the name of the sub-protocol the server selected; this will be one of
       * the strings specified in the protocols parameter when creating the WebSocket object.
       * Read only.
       */
      this.protocol = null;

      // Private state variables

      var self = this;
      var ws;
      var forcedClose = false;
      var timedOut = false;
      var eventTarget = document.createElement('div');

      // Wire up "on*" properties as event handlers

      eventTarget.addEventListener('open',       function(event) { self.onopen(event); });
      eventTarget.addEventListener('close',      function(event) { self.onclose(event); });
      eventTarget.addEventListener('connecting', function(event) { self.onconnecting(event); });
      eventTarget.addEventListener('message',    function(event) { self.onmessage(event); });
      eventTarget.addEventListener('error',      function(event) { self.onerror(event); });

      // Expose the API required by EventTarget

      this.addEventListener = eventTarget.addEventListener.bind(eventTarget);
      this.removeEventListener = eventTarget.removeEventListener.bind(eventTarget);
      this.dispatchEvent = eventTarget.dispatchEvent.bind(eventTarget);

      /**
       * This function generates an event that is compatible with standard
       * compliant browsers and IE9 - IE11
       *
       * This will prevent the error:
       * Object doesn't support this action
       *
       * http://stackoverflow.com/questions/19345392/why-arent-my-parameters-getting-passed-through-to-a-dispatched-event/19345563#19345563
       * @param s String The name that the event should use
       * @param args Object an optional object that the event will use
       */
      function generateEvent(s, args) {
        var evt = document.createEvent("CustomEvent");
        evt.initCustomEvent(s, false, false, args);
        return evt;
      };

      this.open = function (reconnectAttempt) {
          ws = new WebSocket(self.url, protocols || []);
          ws.binaryType = this.binaryType;

          if (reconnectAttempt) {
              if (this.maxReconnectAttempts && this.reconnectAttempts > this.maxReconnectAttempts) {
                  return;
              }
          } else {
              eventTarget.dispatchEvent(generateEvent('connecting'));
              this.reconnectAttempts = 0;
          }

          if (self.debug || ReconnectingWebSocket.debugAll) {
              console.debug('ReconnectingWebSocket', 'attempt-connect', self.url);
          }

          var localWs = ws;
          var timeout = setTimeout(function() {
              if (self.debug || ReconnectingWebSocket.debugAll) {
                  console.debug('ReconnectingWebSocket', 'connection-timeout', self.url);
              }
              timedOut = true;
              localWs.close();
              timedOut = false;
          }, self.timeoutInterval);

          ws.onopen = function(event) {
              clearTimeout(timeout);
              if (self.debug || ReconnectingWebSocket.debugAll) {
                  console.debug('ReconnectingWebSocket', 'onopen', self.url);
              }
              self.protocol = ws.protocol;
              self.readyState = WebSocket.OPEN;
              self.reconnectAttempts = 0;
              var e = generateEvent('open');
              e.isReconnect = reconnectAttempt;
              reconnectAttempt = false;
              eventTarget.dispatchEvent(e);
          };

          ws.onclose = function(event) {
              clearTimeout(timeout);
              ws = null;
              if (forcedClose) {
                  self.readyState = WebSocket.CLOSED;
                  eventTarget.dispatchEvent(generateEvent('close'));
              } else {
                  self.readyState = WebSocket.CONNECTING;
                  var e = generateEvent('connecting');
                  e.code = event.code;
                  e.reason = event.reason;
                  e.wasClean = event.wasClean;
                  eventTarget.dispatchEvent(e);
                  if (!reconnectAttempt && !timedOut) {
                      if (self.debug || ReconnectingWebSocket.debugAll) {
                          console.debug('ReconnectingWebSocket', 'onclose', self.url);
                      }
                      eventTarget.dispatchEvent(generateEvent('close'));
                  }

                  var timeout = self.reconnectInterval * Math.pow(self.reconnectDecay, self.reconnectAttempts);
                  setTimeout(function() {
                      self.reconnectAttempts++;
                      self.open(true);
                  }, timeout > self.maxReconnectInterval ? self.maxReconnectInterval : timeout);
              }
          };
          ws.onmessage = function(event) {
              if (self.debug || ReconnectingWebSocket.debugAll) {
                  console.debug('ReconnectingWebSocket', 'onmessage', self.url, event.data);
              }
              var e = generateEvent('message');
              e.data = event.data;
              eventTarget.dispatchEvent(e);
          };
          ws.onerror = function(event) {
              if (self.debug || ReconnectingWebSocket.debugAll) {
                  console.debug('ReconnectingWebSocket', 'onerror', self.url, event);
              }
              eventTarget.dispatchEvent(generateEvent('error'));
          };
      }

      // Whether or not to create a websocket upon instantiation
      if (this.automaticOpen == true) {
          this.open(false);
      }

      /**
       * Transmits data to the server over the WebSocket connection.
       *
       * @param data a text string, ArrayBuffer or Blob to send to the server.
       */
      this.send = function(data) {
          if (ws) {
              if (self.debug || ReconnectingWebSocket.debugAll) {
                  console.debug('ReconnectingWebSocket', 'send', self.url, data);
              }
              return ws.send(data);
          } else {
              throw 'INVALID_STATE_ERR : Pausing to reconnect websocket';
          }
      };

      /**
       * Closes the WebSocket connection or connection attempt, if any.
       * If the connection is already CLOSED, this method does nothing.
       */
      this.close = function(code, reason) {
          // Default CLOSE_NORMAL code
          if (typeof code == 'undefined') {
              code = 1000;
          }
          forcedClose = true;
          if (ws) {
              ws.close(code, reason);
          }
      };

      /**
       * Additional public API method to refresh the connection if still open (close, re-open).
       * For example, if the app suspects bad data / missed heart beats, it can try to refresh.
       */
      this.refresh = function() {
          if (ws) {
              ws.close();
          }
      };
  }

  /**
   * An event listener to be called when the WebSocket connection's readyState changes to OPEN;
   * this indicates that the connection is ready to send and receive data.
   */
  ReconnectingWebSocket.prototype.onopen = function(event) {};
  /** An event listener to be called when the WebSocket connection's readyState changes to CLOSED. */
  ReconnectingWebSocket.prototype.onclose = function(event) {};
  /** An event listener to be called when a connection begins being attempted. */
  ReconnectingWebSocket.prototype.onconnecting = function(event) {};
  /** An event listener to be called when a message is received from the server. */
  ReconnectingWebSocket.prototype.onmessage = function(event) {};
  /** An event listener to be called when an error occurs. */
  ReconnectingWebSocket.prototype.onerror = function(event) {};

  /**
   * Whether all instances of ReconnectingWebSocket should log debug messages.
   * Setting this to true is the equivalent of setting all instances of ReconnectingWebSocket.debug to true.
   */
  ReconnectingWebSocket.debugAll = false;

  ReconnectingWebSocket.CONNECTING = WebSocket.CONNECTING;
  ReconnectingWebSocket.OPEN = WebSocket.OPEN;
  ReconnectingWebSocket.CLOSING = WebSocket.CLOSING;
  ReconnectingWebSocket.CLOSED = WebSocket.CLOSED;

  return ReconnectingWebSocket;
});