How to concatenate Regex in Javascript?

I am a new to regex and need a little help. I can't seem to make it work when I try to concatenate on line 3.

var method = function(name, url) {
   name = name.replace('/[\[]/', '\\[').replace('/[\]]/', '\\]');
   var regex = new RegExp('[\\?&]' + name + '=([^&]*)'); 
    var results = regex.exec(url);
    return results;
};

What am I missing here? Your help is greatly appreciated.

var regex = new RegExp('[\\?&]' + name + THIS PART IS NOT BEING CONTCATENATED.