定时刷新 开始 结束

<script>
var timeHandler;
function abc(){timeHandler=setTimeout("location.reload()",1000);}
function def(){
if(timeHandler!=undefined){
clearTimeout(timeHandler);
timeHandler=undefined;
}
}
</script>
<input type="button" value="开始刷新" onclick="abc()" />
<input type="button" value="结束刷新" onclick="def()" />