function Querystring(qs) { // optionally pass a querystring to parse
        this.params = new Object()
        this.get=Querystring_get
        
        if (qs == null)
            qs=location.search.substring(1,location.search.length)
        
        if (qs.length == 0) return

// Turn <plus> back to <space>
// See: http://www.w3.org/TR/REC-html40/interact/forms.html#h-17.13.4.1
        qs = qs.replace(/\+/g, ' ')
        var args = qs.split('&') // parse out name/value pairs separated via &
      
// split out each name=value pair
    for (var i=0;i<args.length;i++) {
        var value;
        var pair = args[i].split('=')
        var name = unescape(pair[0])
        
        if (pair.length == 2)
            value = unescape(pair[1])
        else
            value = name
        
        this.params[name] = value
    }
}

function Querystring_get(key, default_) {
    // This silly looking line changes UNDEFINED to NULL
    if (default_ == null) default_ = null;
    
    var value=this.params[key]
    if (value==null) value=default_;
    
    return value
}