禁止刷新页面倒计时

第一种：

<SCRIPT LANGUAGE="JavaScript">
    var intDiff;
    function gradeId(gradeId){
    	if(window.name=='' || window.name == '-1' || isNaN(window.name)){//禁止页面刷新
            if(gradeId==8||gradeId==9){
                intDiff = parseInt(60*40);
            }else{
                intDiff = parseInt(60*30);//倒计时总秒数量
            }
    	}else{
            intDiff = window.name;
    	}
    }
    function CountDown(){
    	if(intDiff>=0){
        	hours = Math.floor(intDiff/3600);
        	minutes = Math.floor((intDiff-hours*3600)/60);
        	seconds = Math.floor(intDiff%60);
        	msg = "距离考试结束还有"+minutes+"分"+seconds+"秒";
        	document.all["timer"].innerHTML = msg;
        	if(intDiff == 5*60) alert('注意，还有5分钟!');
        	--intDiff;
        	window.name = intDiff;
        	console.log(intDiff);
    	}else{
    		clearInterval(timer);
    		alert("考试时间到")
    	}
    }
    //js控制定时执行,每隔一段时间定时执行
    //后台查询执行请求 1s 
    timer = setInterval("CountDown()",1000);
</SCRIPT>
<div id="timer" style="color:red"></div>

 

//js控制延时跳转
//延迟跳转 20min
setTimeout('ys_time_out()', 1000*60*20);