node/node_modules/socket.io-client/lib/transports/jsonp-polling.js

   1
   2 /**
   3  * socket.io
   4  * Copyright(c) 2011 LearnBoost <dev@learnboost.com>
   5  * MIT Licensed
   6  */
   7
   8 (function (exports, io) {
   9
  10   /**
  11    * Expose constructor.
  12    */
  13
  14   exports['jsonp-polling'] = JSONPPolling;
  15
  16   /**
  17    * The JSONP transport creates an persistent connection by dynamically
  18    * inserting a script tag in the page. This script tag will receive the
  19    * information of the Socket.IO server. When new information is received
  20    * it creates a new script tag for the new data stream.
  21    *
  22    * @constructor
  23    * @extends {io.Transport.xhr-polling}
  24    * @api public
  25    */
  26
  27   function JSONPPolling (socket) {
  28     io.Transport['xhr-polling'].apply(this, arguments);
  29
  30     this.index = io.j.length;
  31
  32     var self = this;
  33
  34     io.j.push(function (msg) {
  35       self._(msg);
  36     });
  37   };
  38
  39   /**
  40    * Inherits from XHR polling transport.
  41    */
  42
  43   io.util.inherit(JSONPPolling, io.Transport['xhr-polling']);
  44
  45   /**
  46    * Transport name
  47    *
  48    * @api public
  49    */
  50
  51   JSONPPolling.prototype.name = 'jsonp-polling';
  52
  53   /**
  54    * Posts a encoded message to the Socket.IO server using an iframe.
  55    * The iframe is used because script tags can create POST based requests.
  56    * The iframe is positioned outside of the view so the user does not
  57    * notice it's existence.
  58    *
  59    * @param {String} data A encoded message.
  60    * @api private
  61    */
  62
  63   JSONPPolling.prototype.post = function (data) {
  64     var self = this;
  65
  66     if (!this.form) {
  67       var form = document.createElement('FORM')
  68         , area = document.createElement('TEXTAREA')
  69         , id = this.iframeId = 'socketio_iframe_' + this.index
  70         , iframe;
  71
  72       form.className = 'socketio';
  73       form.style.position = 'absolute';
  74       form.style.top = '-1000px';
  75       form.style.left = '-1000px';
  76       form.target = id;
  77       form.method = 'POST';
  78       area.name = 'd';
  79       form.appendChild(area);
  80       document.body.appendChild(form);
  81
  82       this.form = form;
  83       this.area = area;
  84     }
  85
  86     this.form.action = this.prepareUrl() + '?t=' + (+new Date) + '&i=' + this.index;
  87
  88     function complete () {
  89       initIframe();
  90       self.socket.setBuffer(false);
  91     };
  92
  93     function initIframe () {
  94       if (self.iframe) {
  95         self.form.removeChild(self.iframe);
  96       }
  97
  98       try {
  99         // ie6 dynamic iframes with target="" support (thanks Chris Lambacher)
 100         iframe = document.createElement('<iframe name="'+ self.iframeId +'">');
 101       } catch (e) {
 102         iframe = document.createElement('iframe');
 103         iframe.name = self.iframeId;
 104       }
 105
 106       iframe.id = self.iframeId;
 107
 108       self.form.appendChild(iframe);
 109       self.iframe = iframe;
 110     };
 111
 112     initIframe();
 113
 114     this.area.value = data;
 115
 116     try {
 117       this.form.submit();
 118     } catch(e) {}
 119
 120     if (this.iframe.attachEvent) {
 121       iframe.onreadystatechange = function () {
 122         if (self.iframe.readyState == 'complete') {
 123           complete();
 124         }
 125       };
 126     } else {
 127       this.iframe.onload = complete;
 128     }
 129   };
 130
 131   /**
 132    * Creates a new JSONP poll that can be used to listen
 133    * for messages from the Socket.IO server.
 134    *
 135    * @api private
 136    */
 137
 138   JSONPPolling.prototype.get = function () {
 139     var self = this
 140       , script = document.createElement('SCRIPT');
 141
 142     if (this.script) {
 143       this.script.parentNode.removeChild(this.script);
 144       this.script = null;
 145     }
 146
 147     script.async = true;
 148     script.src = this.prepareUrl() + '/?t=' + (+new Date) + '&i=' + this.index;
 149     script.onerror = function () {
 150       self.onClose();
 151     };
 152
 153     var insertAt = document.getElementsByTagName('script')[0]
 154     insertAt.parentNode.insertBefore(script, insertAt);
 155     this.script = script;
 156   };
 157
 158   /**
 159    * Callback function for the incoming message stream from the Socket.IO server.
 160    *
 161    * @param {String} data The message
 162    * @api private
 163    */
 164
 165   JSONPPolling.prototype._ = function (msg) {
 166     this.onData(msg);
 167     if (this.open) {
 168       this.get();
 169     }
 170     return this;
 171   };
 172
 173   /**
 174    * Checks if browser supports this transport.
 175    *
 176    * @return {Boolean}
 177    * @api public
 178    */
 179
 180   JSONPPolling.check = function () {
 181     return true;
 182   };
 183
 184   /**
 185    * Check if cross domain requests are supported
 186    *
 187    * @returns {Boolean}
 188    * @api public
 189    */
 190
 191   JSONPPolling.xdomainCheck = function () {
 192     return true;
 193   };
 194
 195   /**
 196    * Add the transport to your public io.transports array.
 197    *
 198    * @api private
 199    */
 200
 201   io.transports.push('jsonp-polling');
 202
 203 })(
 204     'undefined' != typeof io ? io.Transport : module.exports
 205   , 'undefined' != typeof io ? io : module.parent.exports
 206 );