<html>
<head>
</head>
<body>
<input type="text" name="mss" id="mss"/>
<form action="./index.html">
<input type="text" value="name" name="name"/>
</form>
<body>
</html>
<script type="text/javascript">
<!--
window.onload=function(){
daojishi();
}
var counttime=90*60;//总秒钟
function daojishi(){
if(counttime>=0){
var ms = counttime%60;//余数 89%60==29秒
var mis = Math.floor(counttime/60);//分钟
if(mis>=60){
var hour=Math.floor(mis/60);
mis=Math.floor((counttime-hour*60*60)/60);
document.getElementById("mss").value=hour+"小时"+mis+"分"+ms+"秒数";
}else if(mis>=1){
document.getElementById("mss").value=mis+"分"+ms+"秒数";
}else{
document.getElementById("mss").value=ms+"秒数";
}
counttime--;
vartt = window.setTimeout("daojishi()",1000);
}else{
window.clearTimeout(vartt);
window.confirm("考试时间结束,请单击提交");
tijiao();
}
}
function tijiao(){
document.forms[0].submit();
}
//-->
</script>
原文：https://www.cnblogs.com/feiwenstyle/p/9519132.html