b38dea0597
Share Gaia assets and adapters, keep private profiles and development documents local, and update both public READMEs.
154 lines
4 KiB
JavaScript
154 lines
4 KiB
JavaScript
/* exported LazyLoader */
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/* globals HtmlImports, Promise */
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'use strict';
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/**
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* This contains a simple LazyLoader implementation
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* To use:
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*
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* LazyLoader.load(
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* ['/path/to/file.js', '/path/to/file.css', 'domNode'], callback
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* );
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*/
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var LazyLoader = (function() {
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function LazyLoader() {
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this._loaded = {};
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this._isLoading = {};
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}
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LazyLoader.prototype = {
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_js: function(file, callback) {
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var script = document.createElement('script');
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script.src = file;
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// until bug 916255 lands async is the default so
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// we must disable it so scripts load in the order they where
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// required.
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script.async = false;
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script.addEventListener('load', callback);
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document.head.appendChild(script);
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this._isLoading[file] = script;
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},
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_css: function(file, callback) {
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var style = document.createElement('link');
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style.type = 'text/css';
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style.rel = 'stylesheet';
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style.href = file;
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document.head.appendChild(style);
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callback();
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},
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_html: function(domNode, callback) {
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// The next few lines are for loading html imports in DEBUG mode
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if (domNode.getAttribute('is')) {
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this.load(['/shared/js/html_imports.js'], function() {
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HtmlImports.populate(callback);
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}.bind(this));
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return;
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}
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for (var i = 0; i < domNode.childNodes.length; i++) {
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if (domNode.childNodes[i].nodeType == document.COMMENT_NODE) {
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domNode.innerHTML = domNode.childNodes[i].nodeValue;
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break;
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}
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}
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window.dispatchEvent(new CustomEvent('lazyload', {
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detail: domNode
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}));
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callback();
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},
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/**
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* Retrieves content of JSON file.
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*
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* @param {String} file Path to JSON file
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* @param {Boolean} mozSystem If xhr should use mozSystem permissions
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* @return {Promise} A promise that resolves to the JSON content
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* or null in case of invalid path. Rejects if an error occurs.
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*/
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getJSON: function(file, mozSystem) {
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return new Promise(function(resolve, reject) {
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var xhr;
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if (mozSystem) {
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xhr = new XMLHttpRequest({mozSystem: true});
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} else {
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xhr = new XMLHttpRequest();
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}
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xhr.open('GET', file, true);
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xhr.responseType = 'json';
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xhr.onerror = function(error) {
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reject(error);
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};
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xhr.onload = function() {
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if (xhr.response !== null) {
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resolve(xhr.response);
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} else {
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reject(new Error('No valid JSON object was found (' +
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xhr.status + ' ' + xhr.statusText + ')'));
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}
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};
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xhr.send();
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});
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},
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load: function(files, callback) {
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var deferred = {};
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deferred.promise = new Promise(resolve => {
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deferred.resolve = resolve;
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});
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if (!Array.isArray(files)) {
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files = [files];
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}
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var loadsRemaining = files.length, self = this;
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function perFileCallback(file) {
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if (self._isLoading[file]) {
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delete self._isLoading[file];
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}
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self._loaded[file] = true;
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if (--loadsRemaining === 0) {
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deferred.resolve();
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if (callback) {
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callback();
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}
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}
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}
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for (var i = 0; i < files.length; i++) {
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var file = files[i];
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if (this._loaded[file.id || file]) {
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perFileCallback(file);
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} else if (this._isLoading[file]) {
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this._isLoading[file].addEventListener(
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'load', perFileCallback.bind(null, file));
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} else {
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var method, idx;
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if (typeof file === 'string') {
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method = file.match(/\.([^.]+)$/)[1];
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idx = file;
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} else {
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method = 'html';
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idx = file.id;
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}
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this['_' + method](file, perFileCallback.bind(null, idx));
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}
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}
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return deferred.promise;
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}
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};
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return new LazyLoader();
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}());
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