                        课程
                    
                        /前端开发
                        
                            /JavaScript
                        
                        /JavaScript进阶篇

终于写对了哭晕

<body>
       <h4>操作成功</h4>
       <p><b id="num">5</b>秒后回到主页&nbsp<a href="javascript:goback">返回</a></p>
   <script>
       var sec=document.getElementById("num").innerHTML;
       function timer(){
           sec--;
           document.getElementById("num").innerHTML=sec;
           if(sec==1){
               window.location.href="http://www.baidu.com";
           }
       }
       setInterval(timer,1000);
       function goback(){
           window.history.back();
       }
   </script>