javascript中派发事件

 1   <script type="text/javascript">
 2       <!--
 3     var dispatchEvent=function(obj,event,fun){
 4     if(obj.attachEvent)
 5         obj.attachEvent(event.indexOf('on')>-1?event:'on'+event,fun);
 6     else
 7         addEventListener(event.indexOf('on')>-1?event.substring(2):event,fun,false);
 8     };
 9     window.onload=function()
10     {
11         alert('1');
12     }
13     function testAlert()
14     {
15         alert('2');
16     }
17     dispatchEvent(window,'onload',testAlert);
18      // -->
19    </script>