js实现的倒计时按钮实例

<span style="font-size: 14px;">
<input type="button" value="确定"id="rulesubmit" />
<scripttypescripttype="text/javascript">
var secs = 3;
var wait = secs * 1000;
var update = function(num,value){
if (num == (wait/1000)){
$("#rulesubmit").val("免费获取");
}
else{
printnr = (wait/1000) - num;
$("#rulesubmit").val("免费获取(" + printnr +")");
}
};
var timer = function(){
$("#rulesubmit").attr("disabled",false);
$("#rulesubmit").val("免费获取");
};
$(function(){
(function(){
function getValidateCode(){
$("#rulesubmit").val("免费获取(" + secs +")");
$("#rulesubmit").attr("disabled",true);
for (i = 1; i <= secs;i++){
window.setTimeout("update(" + i + ")",i*1000);
}
window.setTimeout("timer()",wait);
}
$("#rulesubmit").click(function(){
getValidateCode();
});
})();
//注意，我这里在测试的时候改成里匿名函数，其实不必这样做也可以实现
//getValidateCode()当作一个单独的函数，在$(function(){//点击按钮执行函数，即上面蓝色部分代码;});
});
</script></span>