2013-08-26 18:35:25 +02:00
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/*jslint browser: true, eqeqeq: true, bitwise: true, newcap: true, immed: true, regexp: false */
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2013-09-14 02:55:04 +02:00
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/** @preserve
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Software from "LazyLoad" is Copyright (c) 2011 Ryan Grove <ryan@wonko.com>
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and is provided under the following license:
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--
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Permission is hereby granted, free of charge, to any person obtaining a copy of
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this software and associated documentation files (the 'Software'), to deal in
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the Software without restriction, including without limitation the rights to
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use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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the Software, and to permit persons to whom the Software is furnished to do so,
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subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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--
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/**
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2013-08-26 18:35:25 +02:00
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/**
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LazyLoad makes it easy and painless to lazily load one or more external
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JavaScript or CSS files on demand either during or after the rendering of a web
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page.
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Supported browsers include Firefox 2+, IE6+, Safari 3+ (including Mobile
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Safari), Google Chrome, and Opera 9+. Other browsers may or may not work and
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are not officially supported.
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Visit https://github.com/rgrove/lazyload/ for more info.
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@module lazyload
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@class LazyLoad
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@static
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*/
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LazyLoad = (function (doc) {
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// -- Private Variables ------------------------------------------------------
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// User agent and feature test information.
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var env,
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// Reference to the <head> element (populated lazily).
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head,
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// Requests currently in progress, if any.
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pending = {},
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// Number of times we've polled to check whether a pending stylesheet has
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// finished loading. If this gets too high, we're probably stalled.
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pollCount = 0,
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// Queued requests.
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queue = {css: [], js: []},
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// Reference to the browser's list of stylesheets.
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styleSheets = doc.styleSheets;
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// -- Private Methods --------------------------------------------------------
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/**
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Creates and returns an HTML element with the specified name and attributes.
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@method createNode
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@param {String} name element name
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@param {Object} attrs name/value mapping of element attributes
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@return {HTMLElement}
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@private
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*/
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function createNode(name, attrs) {
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var node = doc.createElement(name), attr;
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for (attr in attrs) {
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if (attrs.hasOwnProperty(attr)) {
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node.setAttribute(attr, attrs[attr]);
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}
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}
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return node;
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}
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/**
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Called when the current pending resource of the specified type has finished
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loading. Executes the associated callback (if any) and loads the next
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resource in the queue.
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@method finish
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@param {String} type resource type ('css' or 'js')
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@private
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*/
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function finish(type) {
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var p = pending[type],
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callback,
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urls;
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if (p) {
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callback = p.callback;
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urls = p.urls;
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urls.shift();
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pollCount = 0;
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// If this is the last of the pending URLs, execute the callback and
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// start the next request in the queue (if any).
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if (!urls.length) {
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callback && callback.call(p.context, p.obj);
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pending[type] = null;
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queue[type].length && load(type);
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}
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}
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}
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/**
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Populates the <code>env</code> variable with user agent and feature test
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information.
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@method getEnv
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@private
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*/
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function getEnv() {
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var ua = navigator.userAgent;
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env = {
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// True if this browser supports disabling async mode on dynamically
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// created script nodes. See
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// http://wiki.whatwg.org/wiki/Dynamic_Script_Execution_Order
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async: doc.createElement('script').async === true
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};
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(env.webkit = /AppleWebKit\//.test(ua))
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|| (env.ie = /MSIE|Trident/.test(ua))
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|| (env.opera = /Opera/.test(ua))
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|| (env.gecko = /Gecko\//.test(ua))
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|| (env.unknown = true);
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}
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/**
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Loads the specified resources, or the next resource of the specified type
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in the queue if no resources are specified. If a resource of the specified
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type is already being loaded, the new request will be queued until the
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first request has been finished.
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When an array of resource URLs is specified, those URLs will be loaded in
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parallel if it is possible to do so while preserving execution order. All
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browsers support parallel loading of CSS, but only Firefox and Opera
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support parallel loading of scripts. In other browsers, scripts will be
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queued and loaded one at a time to ensure correct execution order.
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@method load
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@param {String} type resource type ('css' or 'js')
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@param {String|Array} urls (optional) URL or array of URLs to load
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@param {Function} callback (optional) callback function to execute when the
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resource is loaded
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@param {Object} obj (optional) object to pass to the callback function
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@param {Object} context (optional) if provided, the callback function will
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be executed in this object's context
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@private
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*/
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function load(type, urls, callback, obj, context) {
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var _finish = function () { finish(type); },
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isCSS = type === 'css',
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nodes = [],
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i, len, node, p, pendingUrls, url;
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env || getEnv();
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if (urls) {
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// If urls is a string, wrap it in an array. Otherwise assume it's an
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// array and create a copy of it so modifications won't be made to the
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// original.
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urls = typeof urls === 'string' ? [urls] : urls.concat();
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// Create a request object for each URL. If multiple URLs are specified,
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// the callback will only be executed after all URLs have been loaded.
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//
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// Sadly, Firefox and Opera are the only browsers capable of loading
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// scripts in parallel while preserving execution order. In all other
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// browsers, scripts must be loaded sequentially.
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//
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// All browsers respect CSS specificity based on the order of the link
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// elements in the DOM, regardless of the order in which the stylesheets
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// are actually downloaded.
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if (isCSS || env.async || env.gecko || env.opera) {
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// Load in parallel.
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queue[type].push({
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urls : urls,
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callback: callback,
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obj : obj,
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context : context
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});
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} else {
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// Load sequentially.
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for (i = 0, len = urls.length; i < len; ++i) {
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queue[type].push({
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urls : [urls[i]],
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callback: i === len - 1 ? callback : null, // callback is only added to the last URL
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obj : obj,
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context : context
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});
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}
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}
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}
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// If a previous load request of this type is currently in progress, we'll
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// wait our turn. Otherwise, grab the next item in the queue.
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if (pending[type] || !(p = pending[type] = queue[type].shift())) {
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return;
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}
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head || (head = doc.head || doc.getElementsByTagName('head')[0]);
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pendingUrls = p.urls;
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for (i = 0, len = pendingUrls.length; i < len; ++i) {
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url = pendingUrls[i];
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if (isCSS) {
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node = env.gecko ? createNode('style') : createNode('link', {
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href: url,
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rel : 'stylesheet'
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});
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} else {
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node = createNode('script', {src: url});
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node.async = false;
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}
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node.className = 'lazyload';
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node.setAttribute('charset', 'utf-8');
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if (env.ie && !isCSS && 'onreadystatechange' in node && !('draggable' in node)) {
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node.onreadystatechange = function () {
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if (/loaded|complete/.test(node.readyState)) {
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node.onreadystatechange = null;
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_finish();
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}
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};
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} else if (isCSS && (env.gecko || env.webkit)) {
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// Gecko and WebKit don't support the onload event on link nodes.
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if (env.webkit) {
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// In WebKit, we can poll for changes to document.styleSheets to
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// figure out when stylesheets have loaded.
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p.urls[i] = node.href; // resolve relative URLs (or polling won't work)
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pollWebKit();
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} else {
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// In Gecko, we can import the requested URL into a <style> node and
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// poll for the existence of node.sheet.cssRules. Props to Zach
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// Leatherman for calling my attention to this technique.
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node.innerHTML = '@import "' + url + '";';
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pollGecko(node);
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}
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} else {
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node.onload = node.onerror = _finish;
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}
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nodes.push(node);
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}
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for (i = 0, len = nodes.length; i < len; ++i) {
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head.appendChild(nodes[i]);
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}
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}
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/**
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Begins polling to determine when the specified stylesheet has finished loading
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in Gecko. Polling stops when all pending stylesheets have loaded or after 10
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seconds (to prevent stalls).
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Thanks to Zach Leatherman for calling my attention to the @import-based
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cross-domain technique used here, and to Oleg Slobodskoi for an earlier
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same-domain implementation. See Zach's blog for more details:
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http://www.zachleat.com/web/2010/07/29/load-css-dynamically/
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@method pollGecko
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@param {HTMLElement} node Style node to poll.
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@private
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*/
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function pollGecko(node) {
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var hasRules;
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try {
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// We don't really need to store this value or ever refer to it again, but
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// if we don't store it, Closure Compiler assumes the code is useless and
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// removes it.
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hasRules = !!node.sheet.cssRules;
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} catch (ex) {
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// An exception means the stylesheet is still loading.
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pollCount += 1;
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if (pollCount < 200) {
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setTimeout(function () { pollGecko(node); }, 50);
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} else {
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// We've been polling for 10 seconds and nothing's happened. Stop
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// polling and finish the pending requests to avoid blocking further
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// requests.
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hasRules && finish('css');
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}
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return;
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}
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// If we get here, the stylesheet has loaded.
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finish('css');
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}
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/**
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Begins polling to determine when pending stylesheets have finished loading
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in WebKit. Polling stops when all pending stylesheets have loaded or after 10
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seconds (to prevent stalls).
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@method pollWebKit
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@private
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*/
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function pollWebKit() {
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var css = pending.css, i;
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if (css) {
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i = styleSheets.length;
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// Look for a stylesheet matching the pending URL.
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while (--i >= 0) {
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if (styleSheets[i].href === css.urls[0]) {
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finish('css');
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break;
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}
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}
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pollCount += 1;
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if (css) {
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if (pollCount < 200) {
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setTimeout(pollWebKit, 50);
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} else {
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// We've been polling for 10 seconds and nothing's happened, which may
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// indicate that the stylesheet has been removed from the document
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// before it had a chance to load. Stop polling and finish the pending
|
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|
|
|
// request to prevent blocking further requests.
|
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|
|
|
finish('css');
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
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|
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|
|
|
return {
|
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|
|
|
|
|
|
|
|
/**
|
|
|
|
|
Requests the specified CSS URL or URLs and executes the specified
|
|
|
|
|
callback (if any) when they have finished loading. If an array of URLs is
|
|
|
|
|
specified, the stylesheets will be loaded in parallel and the callback
|
|
|
|
|
will be executed after all stylesheets have finished loading.
|
|
|
|
|
|
|
|
|
|
@method css
|
|
|
|
|
@param {String|Array} urls CSS URL or array of CSS URLs to load
|
|
|
|
|
@param {Function} callback (optional) callback function to execute when
|
|
|
|
|
the specified stylesheets are loaded
|
|
|
|
|
@param {Object} obj (optional) object to pass to the callback function
|
|
|
|
|
@param {Object} context (optional) if provided, the callback function
|
|
|
|
|
will be executed in this object's context
|
|
|
|
|
@static
|
|
|
|
|
*/
|
|
|
|
|
css: function (urls, callback, obj, context) {
|
|
|
|
|
load('css', urls, callback, obj, context);
|
|
|
|
|
},
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
Requests the specified JavaScript URL or URLs and executes the specified
|
|
|
|
|
callback (if any) when they have finished loading. If an array of URLs is
|
|
|
|
|
specified and the browser supports it, the scripts will be loaded in
|
|
|
|
|
parallel and the callback will be executed after all scripts have
|
|
|
|
|
finished loading.
|
|
|
|
|
|
|
|
|
|
Currently, only Firefox and Opera support parallel loading of scripts while
|
|
|
|
|
preserving execution order. In other browsers, scripts will be
|
|
|
|
|
queued and loaded one at a time to ensure correct execution order.
|
|
|
|
|
|
|
|
|
|
@method js
|
|
|
|
|
@param {String|Array} urls JS URL or array of JS URLs to load
|
|
|
|
|
@param {Function} callback (optional) callback function to execute when
|
|
|
|
|
the specified scripts are loaded
|
|
|
|
|
@param {Object} obj (optional) object to pass to the callback function
|
|
|
|
|
@param {Object} context (optional) if provided, the callback function
|
|
|
|
|
will be executed in this object's context
|
|
|
|
|
@static
|
|
|
|
|
*/
|
|
|
|
|
js: function (urls, callback, obj, context) {
|
|
|
|
|
load('js', urls, callback, obj, context);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
};
|
|
|
|
|
})(this.document);
|
