function getQueryString(parameterName) {
    var queryString     = window.location.search.substring(1);
    
    var pairs = queryString.split('&');
    for(var i = 0; i < pairs.length; ++i) {
        var tokens = pairs[i].split('=');
        if(tokens.length != 2)
            continue;
        
        if(tokens[0].toUpperCase() == parameterName.toUpperCase())
            return unescape(tokens[1]);
    }
    
    return('');
}