<!DOCTYPE html>
<html lang="zh-cn">
<head>
<meta charset="UTF-8">
<title>JS Cookie的操作</title>
<script>
//设置 cookie 值的函数
function setCookie(cname,cvalue,exdays){
	var d = new Date();
	d.setTime(d.getTime()+(exdays*24*60*60*1000));
	var expires = "expires="+d.toGMTString();
	document.cookie = cname+"="+cvalue+"; "+expires;
}
//获取 cookie 值的函数
function getCookie(cname){
	var name = cname + "=";
	var ca = document.cookie.split(';');
	for(var i=0; i<ca.length; i++) {
		var c = ca[i].trim();
		if (c.indexOf(name)==0) return c.substring(name.length,c.length);
	}
	return "";
}
//删除 cookie 值的函数
function delCookie(cname){
	document.cookie = cname+"=; expires=Thu, 01 Jan 1970 00:00:00 GMT";
}
//检测 cookie 值的函数
function checkCookie(){
	var user=getCookie("username");
	if (user!=""){
		alert("获取 cookie：" + user);
	}else{
		user = prompt("设置 cookie：","");
  		if (user!="" && user!=null){
    		setCookie("username",user,30);
    	}
	}
}
</script>
</head>
<body οnlοad="checkCookie()">
<div οnclick="delCookie('username');">删除Cookie</div>
</body>
</html>