<input type="submit" value="倒记时开始" name="sub" disabled/>
<script>
var iSecond = 6;
function bao()
{
iSecond--;
if(iSecond>0)
{
document.all.sub.value = '还剩余' + iSecond + '秒';
}
else
{
document.all.sub.disabled=false;
document.all.sub.value = '记时结束';
clearInterval(timer);
}
}
timer = setInterval("bao()",1000);
</script>
