var src = "/Scripts/Test.js";  
    $("<script type = ‘text/javascript‘ src=‘" + src + "‘><\/script>").appendTo("head");  //动态加载
    TestAlert123123();   //调用Test.js中的函数

  <img src="1.jpg" width="200" height="300" />
     <script src="jquery/jquery-1.4.1.js" type="text/javascript"></script>
     <script src="js/hello.js" type="text/javascript"></script>
     <script src="js/world.js" type="text/javascript"></script>

     <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-1.4.1.js", function () {
             //第二步加载hello.js
             loadScript("js/hello.js", function () {
                 //第三步加载world.js
                 loadScript("js/world.js", function () {
 
                 });
             });
         });
     </script>