if ( !options.crossDomain && !headers["X-Requested-With"] ) {
headers["X-Requested-With"] = "XMLHttpRequest";
}

// Set headers
for ( i in headers ) {
// Support: IE<9
// IE's ActiveXObject throws a 'Type Mismatch' exception when setting
// request header to a null-value.
//
// To keep consistent with other XHR implementations, cast the value
// to string and ignore `undefined`.
if ( headers[ i ] !== undefined ) {
xhr.setRequestHeader( i, headers[ i ] + "" );
}
}

// Do send the request
// This may raise an exception which is actually
// handled in jQuery.ajax (so no try/catch here)
xhr.send( ( options.hasContent && options.data ) || null );

// Listener
callback = function( _, isAbort ) {
var status, statusText, responses;

// Was never called and is aborted or complete
if ( callback && ( isAbort || xhr.readyState === 4 ) ) {
// Clean up
delete xhrCallbacks[ id ];
callback = undefined;
xhr.onreadystatechange = jQuery.noop;

// Abort manually if needed
if ( isAbort ) {
if ( xhr.readyState !== 4 ) {
xhr.abort();
}
} else {
responses = {};
status = xhr.status;

// Support: IE<10
// Accessing binary-data responseText throws an exception
// (#11426)
if ( typeof xhr.responseText === "string" ) {
responses.text = xhr.responseText;
}

// Firefox throws an exception when accessing
// statusText for faulty cross-domain requests
try {
statusText = xhr.statusText;
} catch( e ) {
// We normalize with Webkit giving an empty statusText
statusText = "";
}

// Filter status for non standard behaviors

// If the request is local and we have data: assume a success
// (success with no data won't get notified, that's the best we
// can do given current implementations)
if ( !status && options.isLocal && !options.crossDomain ) {
status = responses.text ? 200 : 404;
// IE - #1450: sometimes returns 1223 when it should be 204
} else if ( status === 1223 ) {
status = 204;
}
}
}

// Call complete if needed
if ( responses ) {
complete( status, statusText, responses, xhr.getAllResponseHeaders() );
}
};

if ( !options.async ) {
// if we're in sync mode we fire the callback
callback();
} else if ( xhr.readyState === 4 ) {
// (IE6 & IE7) if it's in cache and has been
// retrieved directly we need to fire the callback
setTimeout( callback );
} else {
// Add to the list of active xhr callbacks
xhr.onreadystatechange = xhrCallbacks[ id ] = callback;
}
},

abort: function() {
if ( callback ) {
callback( undefined, true );
}
}
};
}
});
}

// Functions to create xhrs
function createStandardXHR() {
try {
return new window.XMLHttpRequest();
} catch( e ) {}
}

function createActiveXHR() {
try {
return new window.ActiveXObject( "Microsoft.XMLHTTP" );
} catch( e ) {}
}




// Install script dataType
jQuery.ajaxSetup({
accepts: {
script: "text/javascript, application/javascript, application/ecmascript, application/x-ecmascript"
},
contents: {
script: /(?:java|ecma)script/
},
converters: {
"text script": function( text ) {
jQuery.globalEval( text );
return text;
}
}
});

// Handle cache's special case and global
jQuery.ajaxPrefilter( "script", function( s ) {
if ( s.cache === undefined ) {
s.cache = false;
}
if ( s.crossDomain ) {
s.type = "GET";
s.global = false;
}
});

// Bind script tag hack transport
jQuery.ajaxTransport( "script", function(s) {

// This transport only deals with cross domain requests
if ( s.crossDomain ) {

var script,
head = document.head || jQuery("head")[0] || document.documentElement;

return {

send: function( _, callback ) {

script = document.createElement("script");

script.async = true;

if ( s.scriptCharset ) {
script.charset = s.scriptCharset;
}

script.src = s.url;

// Attach handlers for all browsers
script.onload = script.onreadystatechange = function( _, isAbort ) {

if ( isAbort || !script.readyState || /loaded|complete/.test( script.readyState ) ) {

// Handle memory leak in IE
script.onload = script.onreadystatechange = null;

// Remove the script
if ( script.parentNode ) {
script.parentNode.removeChild( script );
}

// Dereference the script
script = null;

// Callback if not abort
if ( !isAbort ) {
callback( 200, "success" );
}
}
};

// Circumvent IE6 bugs with base elements (#2709 and #4378) by prepending
// Use native DOM manipulation to avoid our domManip AJAX trickery
head.insertBefore( script, head.firstChild );
},

abort: function() {
if ( script ) {
script.onload( undefined, true );
}
}
};
}
});




var oldCallbacks = [],
rjsonp = /(=)\?(?=&|$)|\?\?/;

// Default jsonp settings
jQuery.ajaxSetup({
jsonp: "callback",
jsonpCallback: function() {
var callback = oldCallbacks.pop() || ( jQuery.expando + "_" + ( nonce++ ) );
this[ callback ] = true;
return callback;
}
});

// Detect, normalize options and install callbacks for jsonp requests
jQuery.ajaxPrefilter( "json jsonp", function( s, originalSettings, jqXHR ) {

var callbackName, overwritten, responseContainer,
jsonProp = s.jsonp !== false && ( rjsonp.test( s.url ) ?
"url" :
typeof s.data === "string" && !( s.contentType || "" ).indexOf("application/x-www-form-urlencoded") && rjsonp.test( s.data ) && "data"
);

// Handle iff the expected data type is "jsonp" or we have a parameter to set
if ( jsonProp || s.dataTypes[ 0 ] === "jsonp" ) {

// Get callback name, remembering preexisting value associated with it
callbackName = s.jsonpCallback = jQuery.isFunction( s.jsonpCallback ) ?
s.jsonpCallback() :