EasyUI easyloader.js分析

/**
* easyloader - jQuery EasyUI
*
* Licensed under the GPL:
*   http://www.gnu.org/licenses/gpl.txt
*
* Copyright 2010 stworthy [ stworthy@gmail.com ]
*
*/
(function(){

    //所有插件集合
    var modules = {
        draggable:{
            js:'jquery.draggable.js'
        },
        droppable:{
            js:'jquery.droppable.js'
        },
        resizable:{
            js:'jquery.resizable.js'
        },
        linkbutton:{
            js:'jquery.linkbutton.js',
            css:'linkbutton.css'
        },
        pagination:{
            js:'jquery.pagination.js',
            css:'pagination.css',
            dependencies:['linkbutton']
        },…以下省略…};

// 支持多语言功能
    var locales = {
        'af':'easyui-lang-af.js',
        'bg':'easyui-lang-bg.js',
        'ca':'easyui-lang-ca.js',
        'cs':'easyui-lang-cs.js',
        'da':'easyui-lang-da.js',
        'de':'easyui-lang-de.js',
        'en':'easyui-lang-en.js',
        'fr':'easyui-lang-fr.js',
        'nl':'easyui-lang-nl.js',
        'zh_CN':'easyui-lang-zh_CN.js',
        'zh_TW':'easyui-lang-zh_TW.js'
    };
    var queues = {};

// 动态加载一个js文件
    function loadJs(url, callback){
        var done = false;
        var script = document.createElement('script');
        script.type = 'text/javascript';
        script.language = 'javascript';
        script.src = url;
        script.onload = script.onreadystatechange = function(){
            if (!done && (!script.readyState || script.readyState == 'loaded' || script.readyState == 'complete')){
                done = true;
                script.onload = script.onreadystatechange = null;
                if (callback){
                    callback.call(script);
                }
            }
        }
        document.getElementsByTagName("head")[0].appendChild(script);
    }

// 加载js后，执行callback事件
    function runJs(url, callback){
        loadJs(url, function(){
            document.getElementsByTagName("head")[0].removeChild(this);
            if (callback){
                callback();
            }
        });
    }

//加载css文件
    function loadCss(url, callback){
        var link = document.createElement('link');
        link.rel = 'stylesheet';
        link.type = 'text/css';
        link.media = 'screen';
        link.href = url;
        document.getElementsByTagName('head')[0].appendChild(link);
        if (callback){
            callback.call(link);
        }
    }

//加载单个js文件
    function loadSingle(name, callback){
        queues[name] = 'loading';
        var module = modules[name];
        var jsStatus = 'loading';
        var cssStatus = (easyloader.css && module['css']) ? 'loading' : 'loaded';
        if (easyloader.css && module['css']){
            if (/^http/i.test(module['css'])){
                var url = module['css'];
            } else {
                var url = easyloader.base + 'themes/' + easyloader.theme + '/' + module['css'];
            }
            loadCss(url, function(){
                cssStatus = 'loaded';
                if (jsStatus == 'loaded' && cssStatus == 'loaded'){
                    finish();
                }
            });
        }
        if (/^http/i.test(module['js'])){
            var url = module['js'];
        } else {
            var url = easyloader.base + 'plugins/' + module['js'];
        }
        loadJs(url, function(){
            jsStatus = 'loaded';
            if (jsStatus == 'loaded' && cssStatus == 'loaded'){
                finish();
            }
        });
        function finish(){
            queues[name] = 'loaded';
            easyloader.onProgress(name);
            if (callback){
                callback();
            }
        }
    }

//根据name, 加载modules变量中的相应对象
    function loadModule(name, callback){
        var mm = [];
        var doLoad = false;
        if (typeof name == 'string'){
            add(name);
        } else {
            for(var i=0; i<name.length; i++){
                add(name[i]);
            }
        }
        function add(name){
            if (!modules[name]) return;

//是否有依赖的js项
            var d = modules[name]['dependencies'];
            if (d){
                for(var i=0; i<d.length; i++){
                    add(d[i]);
                }
            }
            mm.push(name);
        }
        function finish(){
            if (callback){
                callback();
            }
            easyloader.onLoad(name);
        }
        var time = 0;
        function loadMm(){
            if (mm.length){
                var m = mm[0];    // the first module
                if (!queues[m]){
                    doLoad = true;
                    loadSingle(m, function(){
                        mm.shift();
                        loadMm();
                    });
                } else if (queues[m] == 'loaded'){
                    mm.shift();
                    loadMm();
                } else {
                    if (time < easyloader.timeout){
                        time += 10;
                        setTimeout(arguments.callee, 10);
                    }
                }
            } else {
                if (easyloader.locale && doLoad == true && locales[easyloader.locale]){
                    var url = easyloader.base + 'locale/' + locales[easyloader.locale];
                    runJs(url, function(){
                        finish();
                    });
                } else {
                    finish();
                }
            }
        }
        loadMm();
    }

//定义对象
    easyloader = {
        modules:modules,
        locales:locales,
        base:'.',
        theme:'default',
        css:true,
        locale:null,
        timeout:2000,
        load: function(name, callback){
            if (/\.css$/i.test(name)){
                if (/^http/i.test(name)){
                    loadCss(name, callback);
                } else {
                    loadCss(easyloader.base + name, callback);
                }
            } else if (/\.js$/i.test(name)){
                if (/^http/i.test(name)){
                    loadJs(name, callback);
                } else {
                    loadJs(easyloader.base + name, callback);
                }
            } else {
                loadModule(name, callback);
            }
        },
        onProgress: function(name){},
        onLoad: function(name){}
    };

    var scripts = document.getElementsByTagName('script');
    for(var i=0; i<scripts.length; i++){
        var src = scripts[i].src;
        if (!src) continue;
        var m = src.match(/easyloader\.js(\W|$)/i);
        if (m){
            easyloader.base = src.substring(0, m.index);
        }
    }

//别名而已， 其实就是调用load方法

    window.using = easyloader.load;
    if (window.jQuery){
        jQuery(function(){

//调用parser项，其实就是加载jquery.parser.js
            easyloader.load('parser', function(){
                jQuery.parser.parse();
            });
        });
    }
})();