js对cookie的写入，读取及删除。

/*
name:cookie 名
value:cookie 值
*/
//写入cookie
function SetCookie(name,value)
{
var Days = 30; //此 cookie 将被保存 30 天
var exp = new Date();
exp.setTime(exp.getTime() + Days*24*60*60*1000);
document.cookie = name + "="+ escape (value) + ";expires=" + exp.toGMTString();
}

///删除cookie
function delCookie(name)
{
var exp = new Date();
exp.setTime(exp.getTime() - 1);
var cval=getCookie(name);
if(cval!=null) document.cookie= name + "="+cval+";expires="+exp.toGMTString();
}

//读取cookie
function getCookie(name)
{
var arr = document.cookie.match(new RegExp("(^| )"+name+"=([^;]*)(;|$)"));
if(arr != null)
return unescape(arr[2]);
return null;
}