js操作cookie

//删除名称为name的Cookie
function DeleteCookie (name) 
{   
    var exp = new Date();
    exp.setTime (exp.getTime() - 1);
   var cval = GetCookie (name);
   document.cookie = name + "=" + cval + "; expires=" + exp.toGMTString();
}
 
//清除COOKIE
function ClearCookies()
{

       var temp=document.cookie.split(";");
       var ts;
       for (var i=0;;i++)
        {
            if(!temp[i])break;
           ts=temp[i].split("=")[0];
           DeleteCookie(ts);
        }
  
}
//取得项名称为offset的cookie值 
function GetCookieVal (offset)
{
    var endstr = document.cookie.indexOf (";", offset);
    if (endstr == -1)
    endstr = document.cookie.length;
    return unescape(document.cookie.substring(offset, endstr));
}
 
//取得名称为name的cookie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 null;
}