Javascript Array first(matching)

Array.prototype.first = function(matching) {
    for (var i = 0; i < this.length; i++) {
 var entry = this[i];
        //from ww  w. j  av  a  2  s  .c  o  m
 if (matching(entry) == true)
     return this[i];
    }

    return null;
}