Function transform

lodash.js:13887–13908

* An alternative to `_.reduce`; this method transforms `object` to a new * `accumulator` object which is the result of running each of its own * enumerable string keyed properties thru `iteratee`, with each invocation * potentially mutating the `accumulator` object. If `accumulator` i

(object, iteratee, accumulator)

     * // => { '1': ['a', 'c'], '2': ['b'] }
     */
    function transform(object, iteratee, accumulator) {
      var isArr = isArray(object),
          isArrLike = isArr || isBuffer(object) || isTypedArray(object);

      iteratee = getIteratee(iteratee, 4);
      if (accumulator == null) {
        var Ctor = object && object.constructor;
        if (isArrLike) {
          accumulator = isArr ? new Ctor : [];
        }
        else if (isObject(object)) {
          accumulator = isFunction(Ctor) ? baseCreate(getPrototype(object)) : {};
        }
        else {
          accumulator = {};
        }
      }
      (isArrLike ? arrayEach : baseForOwn)(object, function(value, index, object) {
        return iteratee(accumulator, value, index, object);
      });
      return accumulator;
    }

    /**
     * Removes the property at `path` of `object`.