Why RegExp not matching?

I'm using Node v.0.8.8.

In the following example, why url isn't being matched with /([\w-]+) regular expression? Is it a bug or am I doing something incorrect?

var patterns = [
    '/([\w-]+)',
    '/.*'
],
    url = '/asdf';

for (var pattern in patterns) {
    var re, match;

    re = new RegExp('^' + patterns[pattern] + '$');

    if ((match = re.exec(url))) {
        console.log(url + ' matched: ' + patterns[pattern])

        // break the loop since we've already found the first match
        return false;
    }
    else{
        console.log(url + ' NOT matched: ' + patterns[pattern])
    }
}