lodash/internal/baseMap.js

import baseEach from './baseEach';
import getLength from './getLength';
import isLength from './isLength';

/**
 * The base implementation of `_.map` without support for callback shorthands
 * and `this` binding.
 *
 * @private
 * @param {Array|Object|string} collection The collection to iterate over.
 * @param {Function} iteratee The function invoked per iteration.
 * @returns {Array} Returns the new mapped array.
 */
function baseMap(collection, iteratee) {
  var index = -1,
      length = getLength(collection),
      result = isLength(length) ? Array(length) : [];

  baseEach(collection, function(value, key, collection) {
    result[++index] = iteratee(value, key, collection);
  });
  return result;
}

export default baseMap;