lodash/lodash.pick/index.js

/**
 * lodash 4.0.1 (Custom Build) <https://lodash.com/>
 * Build: `lodash modularize exports="npm" -o ./`
 * Copyright 2012-2016 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2016 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var baseFlatten = require('lodash._baseflatten'),
    rest = require('lodash.rest');

/**
 * A specialized version of `_.reduce` for arrays without support for
 * iteratee shorthands.
 *
 * @private
 * @param {Array} array The array to iterate over.
 * @param {Function} iteratee The function invoked per iteration.
 * @param {*} [accumulator] The initial value.
 * @param {boolean} [initAccum] Specify using the first element of `array` as the initial value.
 * @returns {*} Returns the accumulated value.
 */
function arrayReduce(array, iteratee, accumulator, initAccum) {
  var index = -1,
      length = array.length;

  if (initAccum && length) {
    accumulator = array[++index];
  }
  while (++index < length) {
    accumulator = iteratee(accumulator, array[index], index, array);
  }
  return accumulator;
}

/**
 * The base implementation of `_.pick` without support for individual
 * property names.
 *
 * @private
 * @param {Object} object The source object.
 * @param {string[]} props The property names to pick.
 * @returns {Object} Returns the new object.
 */
function basePick(object, props) {
  object = Object(object);
  return arrayReduce(props, function(result, key) {
    if (key in object) {
      result[key] = object[key];
    }
    return result;
  }, {});
}

/**
 * Creates an object composed of the picked `object` properties.
 *
 * @static
 * @memberOf _
 * @category Object
 * @param {Object} object The source object.
 * @param {...(string|string[])} [props] The property names to pick, specified
 *  individually or in arrays.
 * @returns {Object} Returns the new object.
 * @example
 *
 * var object = { 'a': 1, 'b': '2', 'c': 3 };
 *
 * _.pick(object, ['a', 'c']);
 * // => { 'a': 1, 'c': 3 }
 */
var pick = rest(function(object, props) {
  return object == null ? {} : basePick(object, baseFlatten(props));
});

module.exports = pick;