js的原始方法动态加载js文件

js的原始方法动态加载js文件

<script type="text/javascript">
         function loadScript(url, callback) {
             var script = document.createElement("script");
             script.type = "text/javascript";

             //IE
             if (script.readyState) {
                 script.onreadystatechange = function () {
                     if (script.readyState == "loaded" || script.readyState == "complete") {
                         script.onreadystatechange = null;
                         callback();
                     }
                 }
             } else {
                 //非IE
                 script.onload = function () {
                     callback();
                 }
             }
             script.src = url;
             document.getElementById("head").appendChild(script);
         }
         //第一步加载jquery类库
         loadScript("jquery/jquery-1.7.js", function () {
             //第二步加载test.js
             loadScript("js/test.js", function () {
                 //第三步加载test1.js
                 loadScript("js/test1.js", function () {

                 });
             });
         });
     </script>