EXTJS 如何动态加载js 具体哪个页面用到哪个js才加载 ，不要一打开主页面就把所有的js加载进来？？

Question

具体的要怎么做呢？请举例说明 谢谢我从网上下了酒店管理系统 他把所有的js 全部加载在index.aspx页面  我觉得影响力客户端打开的速度
</script><script type="text/javascript" src="JS/JSLoader.js"></script>
<script type="text/javascript" src="JS/ALLEvents.js"></script>
<script type="text/javascript" src="JS/RoomType/AddRoomType.js"></script>
<script type="text/javascript" src="JS/RoomType/DeleRoomType.js"></script>
<script type="text/javascript" src="JS/RoomType/EditRoomType.js"></script>
<!--房间类型管理-->
<script type="text/javascript" src="JS/RoomType/RoomTypeManage.js"></script>
<script type="text/javascript" src="JS/OpenRoomInfo/RoomInfoManage.js"></script>
<script type="text/javascript" src="JS/OpenRoomInfo/AddGuestInfo.js"></script>
<script type="text/javascript" src="JS/OpenRoomInfo/OpenRoomInfo.js"></script>
<script type="text/javascript" src="JS/OpenRoomInfo/EditOpenRoomInfo.js"></script>
<script type="text/javascript" src="JS/OpenRoomInfo/DelOpenRoomInfo.js"></script><!--房间信息管理-->
<script type="text/javascript" src="JS/Room/RoomManage.js"></script>
<script type="text/javascript" src="JS/Room/AddRoomInfo.js"></script>
<script type="text/javascript" src="JS/Room/DelRoomInfo.js"></script><script type="text/javascript" src="JS/OpenRoomRecordInfo/OpenRoomRecordInfoManage.js"></script><script type="text/javascript" src="JS/TotalInfo/TotalInfoManage.js"></script><script type="text/javascript" src="JS/GuestInfo/GuestInfoManage.js"></script>
<script type="text/javascript" src="JS/GuestInfo/EditGuestInfo.js"></script>
<script type="text/javascript" src="JS/GuestInfo/DelGuestInfo.js"></script>
</script>
怎么改为动态加载？？？？？？？？？

Answer 1

 // 动态导入js
function include(src,encoding,fun) 
{ 
    var s = document.createElement('script');   
    s.type='text/javascript';
    s.charset=encoding; //'gb2312';
    s.src = src;   
    var tags =$$('head');   
   if(typeof(fun)=='function'){
        if( document.all ){
           s.onreadystatechange = function(){
                if(/(complete|loaded)/.test(this.readyState)){
                      fun(); s.onreadystatechange = null; s.parentNode.removeChild(s); 
                 }};
       }else{
             s.onload = function(){  fun(); s.onload = null; s.parentNode.removeChild(s); };
       }
    } 
    tags[0].appendChild(s); 
};