/*global define:false*/
//TODO : get maximum attempts from parent config
(function () {
"use strict";
var doc = document, head = doc.getElementsByTagName("head")[0], IE7_8_9_StylesheetLimit = 30;
var css = {
version:"0.1.0",
maxAttempts:10,
_jsEscape: function (content) {
return content.replace(/(['\\])/g, '\\$1')
.replace(/[\f]/g, "\\f")
.replace(/[\b]/g, "\\b")
.replace(/[\n]/g, "\\n")
.replace(/[\t]/g, "\\t")
.replace(/[\r]/g, "\\r")
.replace(/[\u2028]/g, "\\u2028")
.replace(/[\u2029]/g, "\\u2029");
},
_getIEVersion:function () {
var rv = -1; // Return value assumes failure.
if (navigator.appName === 'Microsoft Internet Explorer') {
var ua = navigator.userAgent;
var re = new RegExp("MSIE ([0-9]{1,}[\\.0-9]{0,})");
if (re.exec(ua) !== null){
rv = parseFloat(RegExp.$1);
}
}
return rv;
},
_checkIeLimitWorkaround:function (url, callback) {
var loadedWithWorkaround = false;
var version = this._getIEVersion();
var ieAndVersion = (version !== -1 && version <= 9) ? true : false;
try {
//workaround for loading IE 31 stylesheet limit
// (http://blogs.msdn.com/b/ieinternals/archive/2011/05/14/internet-explorer-stylesheet-rule-selector-import-sheet-limit-maximum.aspx)
if (doc.createStyleSheet && doc.styleSheets && doc.styleSheets.length > IE7_8_9_StylesheetLimit) {
var lastStylesheet = doc.styleSheets[doc.styleSheets.length - 1];
lastStylesheet.addImport(url, doc.styleSheets.length - 1);
loadedWithWorkaround = true;
callback();
}
}
catch (e) {
this._onerror(callback, e);
loadedWithWorkaround = false;
}
return loadedWithWorkaround;
},
_getUniqueId:function () {
return"cssPreloader_" + Math.round(Math.random() * 9999999999);
},
_createLink:function (url) {
var link = doc.createElement("link");
link.rel = "stylesheet"; link.type = "text/css"; link.id = this._getUniqueId(); link.href = url;
return link;
},
_isEventSupported:function (element, event) {
var c = document.createElement(element);
event = "on" + event;
var isEventSupported = event in c;
if(!isEventSupported){
c.setAttribute(event, "return;");
isEventSupported = (typeof c[event] === "function");
c = null;
}
return isEventSupported;
},
_loadNative:function (url, callback) {
var link = this._createLink(url);
link.onload = function () {
callback();
};
var that = this;
link.onerror = function () {
that._onerror(callback);
};
head.appendChild(link);
},
_onerror:function (callback, exception) {
if (Object.prototype.toString.call(callback.error) === '[object Function]') {
var err = {message:'Failed to load stylesheet', innerException:exception};
callback.error(err);
}
},
_loadWhenNotSupported:function (url, callback) {
var checkLoaded = function (stylesheetLink, callback, attemptsCount) {
try {
if (attemptsCount < this.maxAttempts) {
var stylesheets = document.styleSheets;
for (var i = 0; i < stylesheets.length; i++) {
var g = stylesheets[i];
var link = g.ownerNode ? g.ownerNode : g.owningElement;
if (link && link.id === stylesheetLink.id) {
//check if stylesheet has cssRules collection,because server can return some html in case of 404 ,making ownerNode to be created
var cssRulesAllowed = true;
var cssRules = null;
//Check if access to rules is allowed,if generates Security exception - looks css from different domain and we can't reliably check rules
try {
//can be also null like in Google chrome or undefined like in IE8,7
if (!g.cssRules) {
//IE7 and IE8 css rules collection
if (g.rules) {
cssRules = g.rules;
}
else {
cssRulesAllowed = false;
}
}
else {
cssRules = g.cssRules;
}
}
catch (e) {
cssRulesAllowed = false;
}
if (cssRulesAllowed) {
if (cssRules && cssRules.length && cssRules.length > 0) {
callback();
return;
}
else {
this._onerror(callback);
return;
}
}
//Can't check for 100% if css is loaded when no access to cssRules (stylesheet from different domain),
//so make optimistic assumption css rules are valid and are applied if has ownerNode with matching id
else {
callback();
}
}
}
var that = this;
setTimeout(function () {
checkLoaded.call(that, stylesheetLink, callback, ++attemptsCount);
}, 100);
}
//not loaded with maximum attempts
else {
this._onerror(callback);
return;
}
}
catch (e) {
this._onerror(callback, e);
return;
}
};
var link = this._createLink(url);
head.appendChild(link);
var that = this, attemptsCount = 0;
//TODO : calculate setTimeout according to wait interval
setTimeout(function () {
checkLoaded.call(that, link, callback, attemptsCount);
}, 100);
},
loadStylesheet:function (url, callback) {
var loadedWithWorkaround = this._checkIeLimitWorkaround(url, callback);
if (!loadedWithWorkaround) {
if (this._isEventSupported("link", "load")) {
this._loadNative(url, callback);
}
else {
this._loadWhenNotSupported(url, callback);
}
}
},
///requireJS interface function - called when css! is called
load:function (name, parentConf, load, config,isBuild) {
try {
var url = parentConf.toUrl(name.search(/\.(css)$/i) === -1 ? name + ".css" : name);
this.loadStylesheet(url, load);
}
catch (e) {
load();
}
}
};
//check if AMD loader uses the code
if ( typeof define === 'function') {
define(['module'],function(){return css;});
}
//put cssLoader on global scope
else{
window.css = css;
}
})();
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