方法如下：
<html>
<head>
<title></title>
<script type="text/javascript">
function Case(i) {
if (i < 10) {
i = "0" + i;
}
return i;
}
function getdata() {
var bnt = document.getElementById("id1")
var date = new Date();
bnt.value =Case( date.getHours()) + ":" + Case(date.getMinutes()) + ":" +Case( date.getSeconds());
}
</script>
</head>
<body>
<input type="button" value="获取时间" id="id1" onclick="setInterval(getdata, 1000)"/>
</body>
</html>