JavaScript实现5秒倒计时自动跳转与按钮交互

<!DOCTYPE html>
<html>
 <head>
 <meta charset="UTF-8">
 <title>倒计时五秒</title>
 <script>
 //使用匿名函数方法
 function countDown(){
 
 var time = document.getElementById("Time");
 //alert(time.innerHTML);
 //获取到id为time标签中的内容，现进行判断
 if(time.innerHTML == 0){
 //等于0时清除计时
 window.location.href="https://www.baidu.com" rel="external nofollow" ;
 }else{
 time.innerHTML = time.innerHTML-1;
 }
 }
 //1000毫秒调用一次
 window.setInterval("countDown()",1000);
 </script>
 <style>
 #Time,#p{
 font-size: 100px;
 text-align: center;
 }
 </style>
 </head>
 <body>
 <p id="Time">5</p>
 </body>
</html>

基于jQuery的倒计时与页面跳转

<script src="jquery-1.8.2.min.js"></script>
<script type="text/javascript">
var i=5;
$(function(){
 setTimeout(function(){
 window.location.href='${ctx}/';
 },5000);//5秒后返回首页
 after();
});
//自动刷新页面上的时间
function after(){
 $("#time").empty().append(i);
 i=i-1;
 setTimeout(function(){
 after();
 },1000);
}
</script>

按钮点击触发的倒计时交互示例

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<script type="text/javascript" src="js/jquery.js"></script>
</head>

<body>
 <input type="button" id="btn" value="免费获取验证码" onclick="settime(this)" />

 <script type="text/javascript"> 
var countdown=5; 
function settime(val) { 
if(countdown != 0){
val.setAttribute("disabled", true); 
val.value="重新发送(" + countdown + ")"; 
countdown--; 
}else {
 val.removeAttribute("disabled"); 
 val.value="免费获取验证码"; 
 countdown = 5;

return;//避免无限循环
 } 
setTimeout(function() {
settime(val) 
},1000) 
}
</script>
</body>
</html>