Javascript Array first(criteria)

Array.prototype.first = function (criteria) {
    if (criteria == null)
        return this[0];

    for (var i = 0; i < this.length; i++) {
        var item = this[i];
        if (criteria(item)) {
            return item;
        }//from ww w . j  a v a 2s  . co  m
    }
    return null;
};