lodash/collection/map.js

var arrayMap = require('../internal/arrayMap'),
    baseCallback = require('../internal/baseCallback'),
    baseMap = require('../internal/baseMap'),
    isArray = require('../lang/isArray');

/**
 * Creates an array of values by running each element in `collection` through
 * `iteratee`. The `iteratee` is bound to `thisArg` and invoked with three
 * arguments; (value, index|key, collection).
 *
 * If a property name is provided for `predicate` the created "_.property"
 * style callback returns the property value of the given element.
 *
 * If an object is provided for `predicate` the created "_.matches" style
 * callback returns `true` for elements that have the properties of the given
 * object, else `false`.
 *
 * @static
 * @memberOf _
 * @alias collect
 * @category Collection
 * @param {Array|Object|string} collection The collection to iterate over.
 * @param {Function|Object|string} [iteratee=_.identity] The function invoked
 *  per iteration. If a property name or object is provided it is used to
 *  create a "_.property" or "_.matches" style callback respectively.
 * @param {*} [thisArg] The `this` binding of `iteratee`.
 * @returns {Array} Returns the new mapped array.
 * @example
 *
 * _.map([1, 2, 3], function(n) { return n * 3; });
 * // => [3, 6, 9]
 *
 * _.map({ 'one': 1, 'two': 2, 'three': 3 }, function(n) { return n * 3; });
 * // => [3, 6, 9] (iteration order is not guaranteed)
 *
 * var users = [
 *   { 'user': 'barney' },
 *   { 'user': 'fred' }
 * ];
 *
 * // using the "_.property" callback shorthand
 * _.map(users, 'user');
 * // => ['barney', 'fred']
 */
function map(collection, iteratee, thisArg) {
  var func = isArray(collection) ? arrayMap : baseMap;
  iteratee = baseCallback(iteratee, thisArg, 3);
  return func(collection, iteratee);
}

module.exports = map;