一个关于时间显示的问题
就是想看时间了，就单击一下，在文本框里显示时间，然后不想看了，再单击，就不显示时间了。
这个代码要怎么改才能符合上边的要求？
<html>
<head>
<script type="text/javascript">
function startTime(){
var d = new Date();
var h = d.getHours();
var m = d.getMinutes();
var s = d.getSeconds();
m = checkTime(m);
s = checkTime(s);
calculate.screen.value = h + ":" + m + ":" + s;
setTimeout('startTime()',500);
}
function checkTime(i){
if (i<10){
i="0" + i;
}
return i;
}
</script>
</head>
<body >
<form name = "calculate" action = "">
<input name = "showTime" type = "button" value = " time " onclick = "startTime()" />
<input name = "screen" type = "text" size = "32" value = "0">
</body>
</html>
[解决办法]
<script type="text/javascript">var tid;var b = true;function startTime(){ if(b) return; clearTimeout(tid); var d = new Date(); var h = d.getHours(); var m = d.getMinutes(); var s = d.getSeconds(); m = m<10?"0"+m:m; s = s<10?"0"+s:s; document.calculate.screen.value = h + ":" + m + ":" + s; tid = setTimeout('startTime()',1000);}</script></head><body > <form name = "calculate" action = ""> <input name = "showTime" type = "button" value = " time " onclick = "b=!b;startTime()" /> <input name = "screen" type = "text" size = "32" value = "0"> </form></body></html>