mapValues.js

var baseCallback = require('../internal/baseCallback'),
    baseForOwn = require('../internal/baseForOwn');

/**
 * Creates an object with the same keys as `object` and values generated by
 * running each own enumerable property of `object` through `iteratee`. The
 * iteratee function is bound to `thisArg` and invoked with three arguments:
 * (value, key, object).
 *
 * If a property name is provided for `iteratee` the created `_.property`
 * style callback returns the property value of the given element.
 *
 * If a value is also provided for `thisArg` the created `_.matchesProperty`
 * style callback returns `true` for elements that have a matching property
 * value, else `false`.
 *
 * If an object is provided for `iteratee` the created `_.matches` style
 * callback returns `true` for elements that have the properties of the given
 * object, else `false`.
 *
 * @static
 * @memberOf _
 * @category Object
 * @param {Object} object The object to iterate over.
 * @param {Function|Object|string} [iteratee=_.identity] The function invoked
 *  per iteration.
 * @param {*} [thisArg] The `this` binding of `iteratee`.
 * @returns {Object} Returns the new mapped object.
 * @example
 *
 * _.mapValues({ 'a': 1, 'b': 2 }, function(n) {
 *   return n * 3;
 * });
 * // => { 'a': 3, 'b': 6 }
 *
 * var users = {
 *   'fred':    { 'user': 'fred',    'age': 40 },
 *   'pebbles': { 'user': 'pebbles', 'age': 1 }
 * };
 *
 * // using the `_.property` callback shorthand
 * _.mapValues(users, 'age');
 * // => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)
 */
function mapValues(object, iteratee, thisArg) {
  var result = {};
  iteratee = baseCallback(iteratee, thisArg, 3);

  baseForOwn(object, function(value, key, object) {
    result[key] = iteratee(value, key, object);
  });
  return result;
}

module.exports = mapValues;