/js/lib/Socket.IO-node/support/socket.io-client/lib/transports/jsonp-polling.js

/**
 * Socket.IO client
 * 
 * @author Guillermo Rauch <guillermo@learnboost.com>
 * @license The MIT license.
 * @copyright Copyright (c) 2010 LearnBoost <dev@learnboost.com>
 */

(function(){
	var io = this.io;
	
	io.JSONP = [];
	
	JSONPPolling = io.Transport['jsonp-polling'] = function(){
		io.Transport.XHR.apply(this, arguments);
		this._insertAt = document.getElementsByTagName('script')[0];
		this._index = io.JSONP.length;
		io.JSONP.push(this);
	};
	
	io.util.inherit(JSONPPolling, io.Transport['xhr-polling']);
	
	JSONPPolling.prototype.type = 'jsonp-polling';
	
	JSONPPolling.prototype._send = function(data){
		var self = this;
		if (!('_form' in this)){
			var form = document.createElement('FORM'),
				area = document.createElement('TEXTAREA'),
				id = this._iframeId = 'socket_io_iframe_' + this._index,
				iframe;
	
			form.style.position = 'absolute';
			form.style.top = '-1000px';
			form.style.left = '-1000px';
			form.target = id;
			form.method = 'POST';
			form.action = this._prepareUrl() + '/' + (+new Date) + '/' + this._index;
			area.name = 'data';
			form.appendChild(area);
			this._insertAt.parentNode.insertBefore(form, this._insertAt);
			document.body.appendChild(form);
	
			this._form = form;
			this._area = area;
		}
	
		function complete(){
			initIframe();
			self._posting = false;
			self._checkSend();
		};
	
		function initIframe(){
			if (self._iframe){
				self._form.removeChild(self._iframe);
			} 
	
			try {
				// ie6 dynamic iframes with target="" support (thanks Chris Lambacher)
				iframe = document.createElement('<iframe name="'+ self._iframeId +'">');
			} catch(e){
				iframe = document.createElement('iframe');
				iframe.name = self._iframeId;
			}
	
			iframe.id = self._iframeId;
	
			self._form.appendChild(iframe);
			self._iframe = iframe;
		};
	
		initIframe();
	
		this._posting = true;
		this._area.value = data;
	
		try {
			this._form.submit();
		} catch(e){}
	
		if (this._iframe.attachEvent){
			iframe.onreadystatechange = function(){
				if (self._iframe.readyState == 'complete') complete();
			};
		} else {
			this._iframe.onload = complete;
		}
	};
	
	JSONPPolling.prototype._get = function(){
		var self = this,
				script = document.createElement('SCRIPT');
		if (this._script){
			this._script.parentNode.removeChild(this._script);
			this._script = null;
		}
		script.async = true;
		script.src = this._prepareUrl() + '/' + (+new Date) + '/' + this._index;
		script.onerror = function(){
			self._onDisconnect();
		};
		this._insertAt.parentNode.insertBefore(script, this._insertAt);
		this._script = script;
	};
	
	JSONPPolling.prototype._ = function(){
		this._onData.apply(this, arguments);
		this._get();
		return this;
	};
	
	JSONPPolling.check = function(){
		return true;
	};
	
	JSONPPolling.xdomainCheck = function(){
		return true;
	};
})();