JavaScript 对cookie的基本操作

//定义
document.cookie="username="+escape(username);//关闭网页就失去cookie 

var Days = 1; //此 cookie 将被保存 30 天 
var exp = new Date(); //new Date("December 31, 9998"); 
exp.setTime(exp.getTime() + Days*24*60*60*1000); 
document.cookie="username="+escape(username)+";expires="+ exp.toGMTString();alert(backinfo); 

//删除 
function deleteCookie() 
{ 
var date=new Date(); 
date.setTime(date.getTime()-100000); 
document.cookie="username=v; expires="+date.toGMTString(); 
window.location="default.aspx"; 
} 

// 取回指定cookie的值 
function getCookie(name) 
{ 
var arg = name + "="; 
var alen = arg.length; 
var clen = document.cookie.length; 
var i = 0; 
while(i < clen) 
{ 
var j = i + alen; 
if (document.cookie.substring(i, j) == arg) 
{ 
return getCookieVal(j); 
} 
i = document.cookie.indexOf(" ", i) + 1; 
if(i == 0) break; 
} 
return; 
} 
function getCookieVal(offset) 
{ 
var endstr = document.cookie.indexOf(";", offset); 
if(endstr == -1) 
{ 
endstr = document.cookie.length; 
} 
return unescape(document.cookie.substring(offset, endstr)); 
}