使用javascript做时间倒数读秒功能的实例

<a class="btn btn-default" onclick="StartExamine();">开始</a> 
<div id="TimeClock" class="col-md-4" ><span class="text-danger hour">00</span> <span class="text-danger minute">00</span> <span class="text-danger seconds">00</span></div>

 var gEaminePapeId = 'dfdfad33434342';
 var gExaminePapeTime = '100'; 
 var gHour = gExaminePapeTime / 60; 
 var gMinute = gExaminePapeTime % 60; 
 var gSeconds = gExaminePapeTime * 60;
 var hour_elem = $("#TimeClock").find('.hour');
 var minute_elem = $("#TimeClock").find('.minute');
 var second_elem = $("#TimeClock").find('.seconds');
 function StartExamine() { 
 //开始计时 
 var timeClik = setInterval('ShowClock()', 1000);
 }
 function ShowClock() { 
 if (gSeconds > 1) {
 gSeconds -= 1;
 var hour = Math.floor((gSeconds / 3600) % 24);
 var minute = Math.floor((gSeconds / 60) % 60);
 var second = Math.floor(gSeconds % 60);
 $(hour_elem).text(hour < 10 ? "0" + hour+":" : hour+":"); //计算小时
 $(minute_elem).text(minute < 10 ? "0" + minute+":" : minute+":"); //计算分钟
 $(second_elem).text(second < 10 ? "0" + second : second); //计算秒杀
 }
 else {
 clearInterval(timeClik);
 //做题时间到
 ForceSubmit();
 }
 } 
 function ForceSubmit() {
 //强制提交答题
 }