List comprehension for JavaScript

collect.js

Object.prototype.collect = function(callback) {
  var result = [];
  for (var key in this) {
    if (this.hasOwnProperty(key)) {
      result.push(callback(this[key], key));
    }
  }
  return result;
};

examples

> ['one', 'two'].collect(function(x) { return x.toUpperCase() })
["ONE", "TWO"]

> ['one', 'two'].collect(function(x, i) { return i+': '+x })
["0: one", "1: two"]

> {'name': 'Thijs van der Vossen', 'twitter': '@thijs' }.collect(function(v, k) { return k+': '+v })
["name: Thijs van der Vossen", "twitter: @thijs"]