JS倒计时，自动提交表单!

 <form id="frm" action="http://www.baidu.com">
 考试还剩余<div id="time"></div>
 </form>
 <script>
     var times = 45 * 60;//剩余时间,单位秒
     var timeDiv = document.getElementById("time");
     var timeObj = null;
     function timer(){
         if(times == 0){
             //倒计时结束，提交表单
             document.getElementById("frm").submit();
             window.clearInterval(timeObj);
             return;
         }
         var t = Math.floor(times/60) +"分"+times%60+"秒"
         timeDiv.innerHTML = t;
         times --;
     }
     timeObj = window.setInterval(timer,1000);
 </script>