[求助]请问这段代码为什么可以不停的循环？
请问这段代码为什么可以不停的循环？定义一个NULL类型的变量又是什么作用？如果想让时间的显示在一个表单的文本框内又该如何显示？本人初学请高手指点，谢谢！<html>
<head>
<script Language="JavaScript">
var timerID = null;
var timerRunning = false;
function stopclock (){
if(timerRunning)
clearTimeout(timerID);
timerRunning = false;
}
function showtime () {
var now = new Date();
var hours = now.getHours();
var minutes = now.getMinutes();
var seconds = now.getSeconds()
var timeValue = "" + ((hours >12) ? hours -12 :hours)
timeValue += ((minutes < 10) ? ":0" : ":") + minutes
timeValue += ((seconds < 10) ? ":0" : ":") + seconds
timeValue += (hours >= 12) ? " P.M." : " A.M."
window.status = timeValue;
timerID = setTimeout("showtime()",1000);
timerRunning = true;
}
function startclock () {
stopclock();
showtime();
}
</script>
</head>
<body onLoad="startclock()">
</body>
</html>
