/*!
* Ext JS Library 3.4.0
* Copyright(c) 2006-2011 Sencha Inc.
* licensing@sencha.com
* http://www.sencha.com/license
*/
/**
* @class Ext.Loader
* @singleton
* Simple class to help load JavaScript files on demand
*/
Ext.Loader = Ext.apply({}, {
/**
* Loads a given set of .js files. Calls the callback function when all files have been loaded
* Set preserveOrder to true to ensure non-parallel loading of files if load order is important
* @param {Array} fileList Array of all files to load
* @param {Function} callback Callback to call after all files have been loaded
* @param {Object} scope The scope to call the callback in
* @param {Boolean} preserveOrder True to make files load in serial, one after the other (defaults to false)
*/
load: function(fileList, callback, scope, preserveOrder) {
var scope = scope || this,
head = document.getElementsByTagName("head")[0],
fragment = document.createDocumentFragment(),
numFiles = fileList.length,
loadedFiles = 0,
me = this;
/**
* Loads a particular file from the fileList by index. This is used when preserving order
*/
var loadFileIndex = function(index) {
head.appendChild(
me.buildScriptTag(fileList[index], onFileLoaded)
);
};
/**
* Callback function which is called after each file has been loaded. This calls the callback
* passed to load once the final file in the fileList has been loaded
*/
var onFileLoaded = function() {
loadedFiles ++;
//if this was the last file, call the callback, otherwise load the next file
if (numFiles == loadedFiles && typeof callback == 'function') {
callback.call(scope);
} else {
if (preserveOrder === true) {
loadFileIndex(loadedFiles);
}
}
};
if (preserveOrder === true) {
loadFileIndex.call(this, 0);
} else {
//load each file (most browsers will do this in parallel)
Ext.each(fileList, function(file, index) {
fragment.appendChild(
this.buildScriptTag(file, onFileLoaded)
);
}, this);
head.appendChild(fragment);
}
},
/**
* @private
* Creates and returns a script tag, but does not place it into the document. If a callback function
* is passed, this is called when the script has been loaded
* @param {String} filename The name of the file to create a script tag for
* @param {Function} callback Optional callback, which is called when the script has been loaded
* @return {Element} The new script ta
*/
buildScriptTag: function(filename, callback) {
var script = document.createElement('script');
script.type = "text/javascript";
script.src = filename;
//IE has a different way of handling <script> loads, so we need to check for it here
if (script.readyState) {
script.onreadystatechange = function() {
if (script.readyState == "loaded" || script.readyState == "complete") {
script.onreadystatechange = null;
callback();
}
};
} else {
script.onload = callback;
}
return script;
}
});