function WriteCookie(cookiename,cookievalue){
//写入cookie //传入参数:cookie名,cookie值
document.cookie=cookiename +"=" + escape(cookievalue); //对cookie值进行编码.目的在于兼容多种浏览器
}
function ReadCookie(cookiename){
//读取cookie
var allcookies=document.cookie ;
var pos=allcookies.indexOf(cookiename+"=") ;
if (pos!=-1){
var start=pos +cookiename.length+1 //从现有的cookie(字符串)中提现有值,(cookie名+"="的长度)
var end=allcookies.indexOf(";",start);
if (end==-1) end=allcookies.length; {
var value= allcookies.substring(start,end); //提取值
value=unescape(value); //解码
return value;
}else return ‘’;
}