https://cryptostorage.com/js/DependencyLoader.js

1/**
2 * MIT License
3 * 
4 * Copyright (c) 2018 cryptostorage
5 * 
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 * 
13 * The above copyright notice and this permission notice shall be included in all
14 * copies or substantial portions of the Software.
15 * 
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 */
24
25// global loader instance
26var LOADER = new DependencyLoader();
27
28/**
29 * Loads dependencies.
30 * 
31 * Requires loadjs.js.
32 */
33function DependencyLoader() {
34	
35	var loadedImages = [];
36	
37	/**
38	 * Loads the given paths.
39	 * 
40	 * @param paths is one or more paths to load as a string or string[]
41	 * @param onDone(err) is invoked when the paths are loaded or fail
42	 * @param maxThreads specifies the maximum number of parallel fetch requests (default 10)
43	 */
44	this.load = function(paths, onDone, maxThreads) {
45		maxThreads = maxThreads || 10;
46		
47		// listify paths
48		if (!isArray(paths)) {
49			assertTrue(isString(paths));
50			paths = [paths];
51		}
52		
53		// collect images and scripts that aren't loaded
54		var imagesToLoad = [];
55		var scriptsToLoad = [];
56		for (var i = 0; i < paths.length; i++) {
57			var path = paths[i];
58			assertDefined(path);
59			if (path.endsWith(".png") || path.endsWith(".jpg") || path.endsWith(".gif")) {
60				if (!arrayContains(loadedImages, path)) imagesToLoad.push(path);
61			} else {
62				if (!loadjs.isDefined(path)) {
63					scriptsToLoad.push(path);
64					loadjs(path, path);
65				}
66			}
67		}
68		
69		// done if everything loaded
70		if (!imagesToLoad.length && !scriptsToLoad.length) {
71			if (onDone) onDone();
72			return;
73		}
74		
75		// simulate load time
76		if (AppUtils.SIMULATED_LOAD_TIME) {
77			setTimeout(function() { loadAsync(); }, AppUtils.SIMULATED_LOAD_TIME);
78		} else loadAsync();
79		
80		// executes functions to fetch scripts and images
81		function loadAsync() {
82			var funcs = [getScriptsFunc(scriptsToLoad), getImagesFunc(imagesToLoad)];
83			async.parallelLimit(funcs, maxThreads, function(err, result) {
84				if (onDone) onDone(err);
85			});
86		}
87		
88		function getScriptsFunc(paths) {
89			return function(onDone) {
90				if (!paths.length) onDone();
91				else {
92					loadjs.ready(paths, {
93						success: onDone,
94						error: function() { onDone(new Error("Failed to load dependencies: " + paths)); }
95					});
96				}
97			}
98		}
99		
100		function getImagesFunc(paths) {
101			return function(onDone) {
102				getImages(paths, function(err) {
103					if (err) onDone(new Error("Failed to load images: " + paths));
104					else {
105						loadedImages = loadedImages.concat(paths);
106						onDone();
107					}
108				});
109			}
110		}
111	}
112	
113	/**
114	 * Determines if the given paths are loaded.
115	 * 
116	 * @param paths is one or more paths to check if loaded
117	 */
118	this.isLoaded = function(paths) {
119		
120		// listify paths
121		if (!isArray(paths)) {
122			assertTrue(isString(paths));
123			paths = [paths];
124		}
125		
126		// check if each path is loaded
127		for (var i = 0; i < paths.length; i++) {
128			if (!arrayContains(loadedImages, paths[i]) && !loadjs.isDefined(paths[i])) return false;
129		}
130		
131		// all paths loaded
132		return true;
133	}
134}