javascript中取得queryString值

function GetQueryValue(searchUrl,queryStringName) 
        { 
            /**//*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 

            CopyRight: 網路有限公司 Joysos.Com 
            Description: 在javascript內實現QueryString 
            
            searchUrl: 查詢字串 document.location.search

            CreatDate: 2004-02-28 
            AuthorName:: WuMeibo wumeibo@joysos.com 
            LastUpdate: 
            ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/ 
            var vStr=""; 
            if (searchUrl==null || searchUrl=="" || queryStringName==null || queryStringName=="") return vStr; 
            //searchUrl = searchUrl.toLowerCase(); 
            //alert(searchUrl); 
            queryStringName += "="; 
            var itmp=searchUrl.indexOf(queryStringName); 
            //alert(itmp);
            if (itmp<0){return vStr;} 
            searchUrl = searchUrl.substr(itmp + queryStringName.length);
            //alert(searchUrl); 
            itmp=searchUrl.indexOf("&"); 
            if (itmp<0) 
            { 
                return searchUrl; 
            } 
            else 
            { 
                searchUrl=searchUrl.substr(0,itmp); 
                return searchUrl; 
            } 
        }