lodash/uniqBy.js

define(['./internal/baseIteratee', './internal/baseUniq'], function(baseIteratee, baseUniq) {

  /**
   * This method is like `_.uniq` except that it accepts `iteratee` which is
   * invoked for each element in `array` to generate the criterion by which
   * uniqueness is computed. The iteratee is invoked with one argument: (value).
   *
   * @static
   * @memberOf _
   * @category Array
   * @param {Array} array The array to inspect.
   * @param {Function|Object|string} [iteratee=_.identity] The iteratee invoked per element.
   * @returns {Array} Returns the new duplicate free array.
   * @example
   *
   * _.uniqBy([2.1, 1.2, 2.3], Math.floor);
   * // => [2.1, 1.2]
   *
   * // using the `_.property` iteratee shorthand
   * _.uniqBy([{ 'x': 1 }, { 'x': 2 }, { 'x': 1 }], 'x');
   * // => [{ 'x': 1 }, { 'x': 2 }]
   */
  function uniqBy(array, iteratee) {
    return (array && array.length)
      ? baseUniq(array, baseIteratee(iteratee))
      : [];
  }

  return uniqBy;
});