This article mainly introduces the countdown code of js anti-refresh for everyone. The implementation code of js countdown has certain reference value. Friends who are interested in js can refer to this article
Recently, I was maintaining the exam system. I accidentally clicked the refresh button during the exam test, but the countdown above was not affected. There are also such examples in several blogs, so I want to take a look. How exactly does it prevent refresh.
If it is written in cs code, we may quickly write out how to prevent refreshing, but we need to carry out front-end development, and the exam is conducted on the page, and the js we have learned will be used here. .
<htmlxmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type"content="text/html; charset=gb2312" />
<title>前端开发</title>
</head>
<body>
<SCRIPT LANGUAGE="JavaScript">
<!--
var maxtime;
if(window.name==''){
maxtime = 1*60;
}else{
maxtime = window.name;
}
function CountDown(){
if(maxtime>=0){
minutes = Math.floor(maxtime/60);
seconds = Math.floor(maxtime%60);
msg = "距离考试结束还有"+minutes+"分"+seconds+"秒";
document.all["timer"].innerHTML = msg;
if(maxtime == 5*60) alert('注意，还有5分钟!');
--maxtime;
window.name = maxtime;
}
else{
clearInterval(timer);
alert("考试时间到，结束!");
}
}
timer = setInterval("CountDown()",1000);
//-->
</SCRIPT>
<p id="timer"style="color:red"></p>
</body>
</html>In fact, the main idea here is that we put the time in a variable. After refreshing, we can then read the data from the variable. We can also use cookie to save the start time and read the cookie first after refreshing. There may be more than just this method. I hope everyone has a better way to communicate.
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