人机交互第十周

<html>
<head>
   <script type="text/javascript">
num=0
function a(){
   for(i=0;i<=100;i++)
     {
    if(i%2==0)
                 num+=i;
      }
   alert(num);
      }
   </script>
</head>
<body>
   <input type="button" value="click me"
   onclick="a()"/>
</body>
</html>
   <input type="button" value="click me"
   onclick="a()"/>
</body>
</html>