I recently released some useful additions to String.prototype over on Github (linky). One of the more useful methods in there is extract. I’m sure something similar to this already exists but I’ve yet to find it.

It’s useful when you need to extract a particular group of every match from a global regular expression. Normally you’d have to use the RegExp.exec method along with a while loop to extract that info, and, that is exactly what’s going on behind the scenes. Have a look:

The code:

String.prototype.extract = function( regex, n ) {
    n = n === undefined ? 0 : n;
    if ( !regex.global ) {
        return this.match(regex)[n] || '';
    var match,
        extracted = [];
    while ( (match = regex.exec(this)) ) {
        extracted[extracted.length] = match[n] || '';
    return extracted;


('hi @rob and @adam, oh and @bob').extract(/@(w+)/g, 1);
    // => ['rob', 'adam', 'bob']

(With the above example, you could achieve it with a simple match() if JavaScript supported look-behinds…)

Thanks for reading! Please share your thoughts with me on Twitter. Have a great day!