动态加载js、css的简单实现代码

/**     * 加载js和css文件     * @param     jsonData.path        前缀路径     * @param     jsonData.url        需要加载的js路径或css路径     * @param     jsonData.type        需要加载的类型 js或css    */     function loadWriteFiles(jsonData)     {       jsonData.path = jsonData.path != undefined ? jsonData.path : "";       if(jsonData.type == "js")       {        document.writeln("<script type='text/javascript' src='"+ jsonData.path + jsonData.url+"'></script>");       }       else if(jsonData.type == "css")       {        document.writeln("<link rel='stylesheet' href='"+jsonData.path + jsonData.url+"' type='text/css' />");       }     }          /**     * 加载js或css到head中     * @param     jsonData.path        前缀路径     * @param     jsonData.url        需要加载的js路径或css路径     * @param     jsonData.type        需要加载的类型 js或css     */     function loadFilesToHead(jsonData)     {       jsonData.path = jsonData.path != undefined ? jsonData.path : "";       if(jsonData.type == "js")       {         var _js = document.createElement("script");         _js.setAttribute("type", "text/javascript");         _js.setAttribute("src", jsonData.path + jsonData.url);         _js.onload = _js.onreadystatechange=function(){            if(!this.readyState||this.readyState=='loaded'||this.readyState=='complete'){              if("function" == typeof(jsonData["callback"]) && jsonData["callback"]){                jsonData["callback"].call(this);             }           }            _js.onload=_js.onreadystatechange=null;          }          document.getElementsByTagName("head")[0].appendChild(_js);//追加到head标签内       }       else if(jsonData.type == "css")       {         var _css = document.createElement("link");         _js.setAttribute("type", "text/css");         _css.setAttribute("rel", "stylesheet");         _css.setAttribute("href", jsonData.path + jsonData.url);         document.getElementsByTagName("head")[0].appendChild(_css);//追加到head标签内       }     }

var uiLoad = uiLoad || {};(function($, $document, uiLoad) {  "use strict";  var loaded = [],  promise = false,  deferred = $.Deferred();  uiLoad.load = function (srcs) {    srcs = $.isArray(srcs) ? srcs : srcs.split(//s+/);    if(!promise){      promise = deferred.promise();    }   $.each(srcs, function(index, src) {    promise = promise.then( function(){      return src.indexOf('.css') >=0 ? loadCSS(src) : loadScript(src);    } );   });   deferred.resolve();   return promise;  };  var loadScript = function (src) {    if(loaded[src]) return loaded[src].promise();    var deferred = $.Deferred();    var script = $document.createElement('script');    script.src = src;    script.onload = function (e) {      deferred.resolve(e);    };    script.onerror = function (e) {      deferred.reject(e);    };    $document.body.appendChild(script);    loaded[src] = deferred;    return deferred.promise();  };  var loadCSS = function (href) {    if(loaded[href]) return loaded[href].promise();    var deferred = $.Deferred();    var style = $document.createElement('link');    style.rel = 'stylesheet';    style.type = 'text/css';    style.href = href;    style.onload = function (e) {      deferred.resolve(e);    };    style.onerror = function (e) {      deferred.reject(e);    };    $document.head.appendChild(style);    loaded[href] = deferred;    return deferred.promise();  }})(jQuery, document, uiLoad);