跳转提示页面代码过程@慕课网原创_慕课网

<!DOCTYPE html>
<html>
 <head>
  <title>浏览器对象</title>  
  <meta http-equiv="Content-Type" content="text/html; charset=gb2312"/>   
 </head>
 <body>
  <H4>操作成功</H4>
  <p>
     <b id="second">5</b>秒后回到主页&nbsp;<a href="javascript:goBack();">返回</a>  
  </p>

<script type="text/javascript">  

    var sec = document.getElementById("second");
    var i = 5;
    var timer = setInterval(function(){
        i--;
        **sec.innerHTML = i;//**这里出错
        if(i==1){
            window.location.href =  "http://www.imooc.com/";
        }
    },1000);

  function goBack(){ 
    window.history.go(-1);
  }  
  </script> 
 </body>
</html>