?<div>

? ? <span id="time">5</span>

? ? <span>秒后返回主頁</span>

? ? <a href="" onclick="go()">返回</a>

? ?</div>

<script>

???? function go(){

???????? history.go(-1);

???????? }

????????? ?var num=5;

???? function jishi(){

???????? document.getElementById("time").innerText=num;

???????? if(num==0){

???????? window.open("https://www.baidu.com",'_blank','width:600','height:400');

???????? clearInterval(insd);

???????? }else{

???????? num=num-1;

???????? }

???????? }

???????? var insd=setInterval("jishi()",1000);

</script>