//构造过期日期。其功能是得到从现在开始、后推指定时间后GMT格式的日期。
    //参数days指定后推的天数；hours指定后推的小时数；minutes指定后推的分钟数
    //比如，我希望某个Cookie的过期日期为三天两小时二十一分，
    //那么传递给该函数的参数值依次为3、2、21
    //这三个参数都是必须参数，你可以为它们传递值0
var expires;
    function getExpDate(days, hours, minutes) {
      var expDate = new Date( );
      if (typeof days == "number" && typeof hours == "number" && 
        typeof hours == "number") {
        expDate.setDate(expDate.getDate( ) + parseInt(days));
        expDate.setHours(expDate.getHours( ) + parseInt(hours));
        expDate.setMinutes(expDate.getMinutes( ) + parseInt(minutes));
        return expDate.toGMTString( );
      }
    }
   
    // 得到第offset个Cookie值对儿。该函数由getCookie()函数调用
    function getCookieVal(offset) {
      var endstr = document.cookie.indexOf (";", offset);
      if (endstr == -1) {
        endstr = document.cookie.length;
      }
      return unescape(document.cookie.substring(offset, endstr));
    }
   
    // 根据Cookie名称得到Cookie值
    function getCookie_old(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 "";
    }
    // 根据Cookie名称得到Cookie值
    function getCookie(name) {
   

      if(getCookie_old(name) == null )
      {	
		return "";
      }
      if(getCookie_old(name) == "")
      {	
		return "";
      }
      
	return getCookie_old(name);
      
    }
   
    // 创建或修改Cookie
    function setCookie(name, value, domain, expires) {
      document.cookie = name + "=" + escape (value) +
        ((domain) ? "; domain=" + domain : "")
		if(expires!=null||expires!=0){
			expire = new Date((new Date()).getTime() + expires * 3600000);
			+((expires) ? "; expires=" + expire.toGMTString() : "")
		} 
    }
    // 创建或修改Cookie (2)
    function SetCookieTwo(name,value)
	{
		var Days = 30; 
		var expTime  = new Date();
		expTime.setTime(expTime.getTime() + Days*24*60*60*1000);
		document.cookie = name + "="+ escape (value) + ";expires=" + expTime.toGMTString()+";path=/";
	}
   
    // 删除Cookie
    function deleteCookie(name,domain) {
      if (getCookie(name)) {
        document.cookie = name + "=" +
            ((domain) ? "; domain=" + domain : "") +
            "; expires=Thu, 01-Jan-70 00:00:01 GMT";
      }
    }