Method load

src/js/core/Load.js:158–259

Loads the specified resources, or the next resource of the specified type in the queue if no resources are specified. If a resource of the specified type is already being loaded, the new request will be queued until the first request has been finished. When an array of resource URLs

(type, urls, callback, obj, context)

    @private
    */
    load(type, urls, callback, obj, context) {
        var _finish = function() { this.finish(type); }.bind(this),
            isCSS = type === 'css',
            nodes = [],
            i, len, node, p, pendingUrls, url;



        if (urls) {
            // If urls is a string, wrap it in an array. Otherwise assume it's an
            // array and create a copy of it so modifications won't be made to the
            // original.
            urls = typeof urls === 'string' ? [urls] : urls.concat();

            // Create a request object for each URL. If multiple URLs are specified,
            // the callback will only be executed after all URLs have been loaded.
            //
            // Sadly, Firefox and Opera are the only browsers capable of loading
            // scripts in parallel while preserving execution order. In all other
            // browsers, scripts must be loaded sequentially.
            //
            // All browsers respect CSS specificity based on the order of the link
            // elements in the DOM, regardless of the order in which the stylesheets
            // are actually downloaded.
            if (isCSS || this.env.async || this.env.gecko || this.env.opera) {
                // Load in parallel.
                this.queue[type].push({
                    urls: urls,
                    callback: callback,
                    obj: obj,
                    context: context
                });
            } else {
                // Load sequentially.
                for (i = 0, len = urls.length; i < len; ++i) {
                    this.queue[type].push({
                        urls: [urls[i]],
                        callback: i === len - 1 ? callback : null, // callback is only added to the last URL
                        obj: obj,
                        context: context
                    });
                }
            }
        }

        // If a previous load request of this type is currently in progress, we'll
        // wait our turn. Otherwise, grab the next item in the queue.
        if (this.pending[type] || !(p = this.pending[type] = this.queue[type].shift())) {
            return;
        }


        pendingUrls = p.urls;

        for (i = 0, len = pendingUrls.length; i < len; ++i) {
            url = pendingUrls[i];

            if (isCSS) {