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/**
* socket.io
* Copyright(c) 2011 LearnBoost <dev@learnboost.com>
* MIT Licensed
*/
(function (exports, io, global) {
/**
* Expose constructor.
*/
exports['xhr-polling'] = XHRPolling;
/**
* The XHR-polling transport uses long polling XHR requests to create a
* "persistent" connection with the server.
*
* @constructor
* @api public
*/
function XHRPolling () {
io.Transport.XHR.apply(this, arguments);
};
/**
* Inherits from XHR transport.
*/
io.util.inherit(XHRPolling, io.Transport.XHR);
/**
* Merge the properties from XHR transport
*/
io.util.merge(XHRPolling, io.Transport.XHR);
/**
* Transport name
*
* @api public
*/
XHRPolling.prototype.name = 'xhr-polling';
/**
* Indicates whether heartbeats is enabled for this transport
*
* @api private
*/
XHRPolling.prototype.heartbeats = function () {
return false;
};
/**
* Establish a connection, for iPhone and Android this will be done once the page
* is loaded.
*
* @returns {Transport} Chaining.
* @api public
*/
XHRPolling.prototype.open = function () {
var self = this;
io.Transport.XHR.prototype.open.call(self);
return false;
};
/**
* Starts a XHR request to wait for incoming messages.
*
* @api private
*/
function empty () {};
XHRPolling.prototype.get = function () {
if (!this.isOpen) return;
var self = this;
function stateChange () {
if (this.readyState == 4) {
this.onreadystatechange = empty;
if (this.status == 200) {
self.onData(this.responseText);
self.get();
} else {
self.onClose();
}
}
};
function onload () {
this.onload = empty;
this.onerror = empty;
self.retryCounter = 1;
self.onData(this.responseText);
self.get();
};
function onerror () {
self.retryCounter ++;
if(!self.retryCounter || self.retryCounter > 3) {
self.onClose();
} else {
self.get();
}
};
this.xhr = this.request();
if (global.XDomainRequest && this.xhr instanceof XDomainRequest) {
this.xhr.onload = onload;
this.xhr.onerror = onerror;
} else {
this.xhr.onreadystatechange = stateChange;
}
this.xhr.send(null);
};
/**
* Handle the unclean close behavior.
*
* @api private
*/
XHRPolling.prototype.onClose = function () {
io.Transport.XHR.prototype.onClose.call(this);
if (this.xhr) {
this.xhr.onreadystatechange = this.xhr.onload = this.xhr.onerror = empty;
try {
this.xhr.abort();
} catch(e){}
this.xhr = null;
}
};
/**
* Webkit based browsers show a infinit spinner when you start a XHR request
* before the browsers onload event is called so we need to defer opening of
* the transport until the onload event is called. Wrapping the cb in our
* defer method solve this.
*
* @param {Socket} socket The socket instance that needs a transport
* @param {Function} fn The callback
* @api private
*/
XHRPolling.prototype.ready = function (socket, fn) {
var self = this;
io.util.defer(function () {
fn.call(self);
});
};
/**
* Add the transport to your public io.transports array.
*
* @api private
*/
io.transports.push('xhr-polling');
})(
'undefined' != typeof io ? io.Transport : module.exports
, 'undefined' != typeof io ? io : module.parent.exports
, this
);
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