JS querystring

// http://www.a.com/db/bb4fgzyey?a=d%20ABC&r=efkk&rl=dfv3
function query(param) {
    var regx = eval("/" + param + "=\\S*/gi");
    var match = regx.exec(location.search);
    if (match && match.length > 0) {
        console.log(match[0]);
        var str = match[0].split("&")[0];
        str = str.replace(param + "=", "");
        return str;
    }
    return "";
}

query("a"); //d%20ABC

/r=\S*/gi.exec(location.search)[0].split("&")[0].replace("r=","")

or 

location.search.match(/r=\S*/gi)[0].split("&")[0].replace("r=","")