www.moparisthebest.com/themes/classic/source/javascripts/libs/jXHR.js

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// jXHR.js (JSON-P XHR)
// v0.1 (c) Kyle Simpson
// MIT License
(function(global){
var SETTIMEOUT = global.setTimeout, // for better compression
doc = global.document,
callback_counter = 0;
global.jXHR = function() {
var script_url,
script_loaded,
jsonp_callback,
scriptElem,
publicAPI = null;
function removeScript() { try { scriptElem.parentNode.removeChild(scriptElem); } catch (err) { } }
function reset() {
script_loaded = false;
script_url = "";
removeScript();
scriptElem = null;
fireReadyStateChange(0);
}
function ThrowError(msg) {
try { publicAPI.onerror.call(publicAPI,msg,script_url); } catch (err) { throw new Error(msg); }
}
function handleScriptLoad() {
if ((this.readyState && this.readyState!=="complete" && this.readyState!=="loaded") || script_loaded) { return; }
this.onload = this.onreadystatechange = null; // prevent memory leak
script_loaded = true;
if (publicAPI.readyState !== 4) ThrowError("Script failed to load ["+script_url+"].");
removeScript();
}
function fireReadyStateChange(rs,args) {
args = args || [];
publicAPI.readyState = rs;
if (typeof publicAPI.onreadystatechange === "function") publicAPI.onreadystatechange.apply(publicAPI,args);
}
publicAPI = {
onerror:null,
onreadystatechange:null,
readyState:0,
open:function(method,url){
reset();
internal_callback = "cb"+(callback_counter++);
(function(icb){
global.jXHR[icb] = function() {
try { fireReadyStateChange.call(publicAPI,4,arguments); }
catch(err) {
publicAPI.readyState = -1;
ThrowError("Script failed to run ["+script_url+"].");
}
global.jXHR[icb] = null;
};
})(internal_callback);
script_url = url.replace(/=\?/,"=jXHR."+internal_callback);
fireReadyStateChange(1);
},
send:function(){
SETTIMEOUT(function(){
scriptElem = doc.createElement("script");
scriptElem.setAttribute("type","text/javascript");
scriptElem.onload = scriptElem.onreadystatechange = function(){handleScriptLoad.call(scriptElem);};
scriptElem.setAttribute("src",script_url);
doc.getElementsByTagName("head")[0].appendChild(scriptElem);
},0);
fireReadyStateChange(2);
},
setRequestHeader:function(){}, // noop
getResponseHeader:function(){return "";}, // basically noop
getAllResponseHeaders:function(){return [];} // ditto
};
reset();
return publicAPI;
};
})(window);