<!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>倒计时例子</title>
</head>
<body>
<button onclick="send()" id="btn">发送</button>
</body>
<script>
var seconds = 4
function send(){
var btn = document.getElementById('btn');
btn.setAttribute('disabled',true)
var timer = setInterval(function(){
btn.innerHTML = seconds + 's'
seconds --;
if(seconds<0){
clearInterval(timer)
btn.innerHTML = '发送'
seconds = 4
btn.removeAttribute('disabled')
}
},1000)
}
</script>
</html>
