//写cookies函数
//参数，一个是cookie的名子，一个是值,一个是天数
function setcookie(name, value, days)
{
	var exp   = new date(); //new date("december 31, 9998");
	exp.settime(exp.gettime() + days*24*60*60*1000);
	document.cookie = name + "="+ escape (value) + ";path=/;expires=" + exp.togmtstring();
}

 
//取cookies函数
function getcookie(name)
{
	var arr = document.cookie.match(new regexp("(^| )"+name+"=([^;]*)(;|$)"));
	if(arr != null) return unescape(arr[2]);
	return null;

}
//删除cookie
function delcookie(name)
{
	var exp = new date();
	exp.settime(exp.gettime() - 1);
	var cval=null;//getcookie(name);
	//if(cval!=null) 
	document.cookie= name + "="+cval+";expires="+exp.togmtstring();
}