<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta http-equiv="X-UA-Compatible" content="ie=edge" />
<title>Document</title>
</head>
<body>
<button onclick="btn()">1</button>
</body>
<script>
function btn() {
let a = 10
let timer = setInterval(function() {
if (a > 0) {
a -= 1
console.log(a)
}
if (a == 0) {
//当倒计时为0,清除计时器,防止下一次计时器越跑越快
clearInterval(timer)
}
}, 1000)
}
</script>
</html>