string before dynamic text regexp, return repetitive array result

Question

I'm trying to get some string before '_', I managed to do that using regexp and make it dynamically, but somehow it returns in array form with 2 repeat answer. I know I could just get like array[0] and pass it over, but it doesn't looks straightforward. What have I done wrong?

function stringBefore($string:String, $before:String):void {
        var s:String = $string;         
        var start:RegExp = /^([^/;
        var end:RegExp = /]*)/g;
        var completeRegExp:RegExp = new RegExp(start.source + $before + end.source);

        trace(s.match(completeRegExp))
    }

Exp: Passing something like 'SFX_SOUND' I will get [SFX, SFX] in an array

Answer 1

You cannot combine regexes that way. You can only combine string patterns and then compile a regex object. So, you might want to fix your code like this:

var start:RegExp = "^([^";
var end:RegExp = "]*)";
var completeRegExp:RegExp = new RegExp(start.source + $before + end.source, "g");

Or, maybe just using strings

var start:String = "^([^";
var end:String = "]*)";
var completeRegExp:RegExp = new RegExp(start + $before + end, "g");