郁闷，不说了，调了一下午的JS啊！

终于明白了setTimeout()与clearTimeout()的区别
<input type = text id = aaa >
<input type = button value = stop id = bb onclick = bb()>
<script>
var iTime


function aa()
{
    aaa.value += "！";
iTime=setTimeout("aa()",600);

}
function bb()
{
if (iTime !="")
clearTimeout(iTime);
}
aa();
</script>