為什么我點擊取消計時器，沒反應呢？
<!DOCTYPE?HTML>
<html>
<head>
<meta?http-equiv="Content-Type"?content="text/html;?charset=utf-8">
<title>計時器</title>
<script?type="text/javascript">
??var?attime
???function?clock(){
??????var?time=new?Date();??????????????? ??
??????document.getElementById("clock").value?=?time;
???}
?i=setInterval(clock,100)????
</script>
</head>
<body>
??<form>
????<input?type="text"?id="clock"?size="50"??/>
????<input?type="button"?value="Stop"??/>
??</form>
</body>
</html>
2015-09-14