一个实现了在按钮上显示倒计时，倒计时完毕自动将按钮设置为不可用的效果，具体代码如下：
<html>
<head>
<title>test count down button</title>
<script src="http://www.maopiaopiao.com/js/jquery.js" type="text/javascript"></script>
<script type="text/javascript">
$(function () {
$('#btn').click(function () {
var count = 3;
var countdown = setInterval(CountDown, 1000);
function CountDown() {
$("#btn").attr("disabled", true);
$("#btn").val("Please wait " + count + " seconds!");
if (count == 0) {
$("#btn").val("Submit").removeAttr("disabled");
clearInterval(countdown);
}
count--;
}
})
});
</script>
</head>
<body>
<input type="button" id="btn" value="Submit" />
</body>
</html>