效果如下：
JS区域实现：
<script>
document.addEventListener('DOMContentLoaded',function(){
var hour=document.querySelector('.left');
var minute=document.querySelector('.center');
var second=document.querySelector('.right');
timer();
var clock=window.setInterval(function(){
timer();
},1000)
function timer(){
var nowtime= +new Date();
var aimtime= +new Date("2022-3-8 19:30:00");
time=(aimtime-nowtime)/1000;
var h=parseInt(time/60/60%24);
h=h<10?'0'+h:h;
hour.innerHTML=h;
var m=parseInt(time/60%60);
m=m<10?'0'+m:m;
minute.innerHTML=m;
var s=parseInt(time%60);
s=s<10?'0'+s:s;
second.innerHTML=s;
}
})
</script>
完整代码实现：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
*{
margin: 0px;
padding: 0px;
}
.box{
box-sizing: border-box;
margin: 100px auto;
width: 500px;
height: 600px;
background-color: rgb(216, 0, 0);
}
.top{
box-sizing: border-box;
width: 500px;
height: 350px;
padding: 5px;
padding-top: 35px;
text-align: center;
line-height: 130px;
font-size: 70px;
color: rgb(255, 255, 255);
font-weight: bold;
}
.bottom{
padding: 10px;
}
.left{
box-sizing: border-box;
margin: 10px;
float: left;
width: 140px;
height: 140px;
background-color: rgb(0, 0, 0);
color: azure;
padding: 19px;
font-size: 80px;
font-weight: bold;
}
.center{
box-sizing: border-box;
margin: 10px;
float: left;
width: 140px;
height: 140px;
background-color: rgb(0, 0, 0);
color: azure;
padding: 19px;
font-size: 80px;
font-weight: bold;
}
.right{
box-sizing: border-box;
margin: 10px;
float: left;
width: 140px;
height: 140px;
background-color: rgb(0, 0, 0);
color: azure;
padding: 19px;
font-size: 80px;
font-weight: bold;
}
</style>
</head>
<body>
<script>
document.addEventListener('DOMContentLoaded',function(){
var hour=document.querySelector('.left');
var minute=document.querySelector('.center');
var second=document.querySelector('.right');
timer();
var clock=window.setInterval(function(){
timer();
},1000)
function timer(){
var nowtime= +new Date();
var aimtime= +new Date("2022-3-8 19:30:00");
time=(aimtime-nowtime)/1000;
var h=parseInt(time/60/60%24);
h=h<10?'0'+h:h;
hour.innerHTML=h;
var m=parseInt(time/60%60);
m=m<10?'0'+m:m;
minute.innerHTML=m;
var s=parseInt(time%60);
s=s<10?'0'+s:s;
second.innerHTML=s;
}
})
</script>
<div class="box">
<div class="top">11.11<br>秒杀倒计时</div>
<div class="bottom">
<div class="left"></div>
<div class="center"></div>
<div class="right"></div>
</div>
</div>
</body>
</html>