<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>document</title>
<style>
body,
html {
height: 100%;
}
div {
display: fixed;
left: 0;
right: 0;
top: 0;
bottom: 0;
margin: auto;
height: 300px;
width: 500px;
line-height: 300px;
text-align: center;
background-color: #ccc;
margin-top: 100px;
}
div span {
color: red;
}
</style>
</head>
<body>
<div>
<h1>这是一则广告，在<span>5</span>秒后自动关闭！</h1>
</div>
<script>
function closeAds() {
document.getElementById('ads').style.display = "none";
}
var oCount5s = document.getElementById("count5s").innerText
var second = parseInt(oCount5s)
function countDown() {
second -= 1;
document.getElementById("count5s").innerText = second;
}
var countDown = setInterval(countDown, 1000)
setInterval(function () {
if (second === 0) {
closeAds();
clearInterval(countDown);
}
}, 1000)
</script>
</body>
</html>