@segment/analytics.js-core/lib/utils/map.js

The hassle-free way to integrate analytics into any web application.

'use strict';

/*
 * The MIT License (MIT) 
 * Copyright (c) 2015 Nathan Houle 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions: 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software. 
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

/*
 * Module dependencies.
 */

var each = require('./each');

/**
 * Produce a new array by passing each value in the input `collection` through a transformative
 * `iterator` function. The `iterator` function is passed three arguments:
 * `(value, index, collection)`.
 *
 * @name map
 * @api public
 * @param {Function} iterator The transformer function to invoke per iteration.
 * @param {Array} collection The collection to iterate over.
 * @return {Array} A new array containing the results of each `iterator` invocation.
 * @example
 * var square = function(x) { return x * x; };
 *
 * map(square, [1, 2, 3]);
 * //=> [1, 4, 9]
 */
var map = function map(iterator, collection) {
  if (typeof iterator !== 'function') {
    throw new TypeError(
      'Expected a function but received a ' + typeof iterator
    );
  }

  var result = [];

  each(function(val, i, collection) {
    result.push(iterator(val, i, collection));
  }, collection);

  return result;
};

/*
 * Exports.
 */

module.exports = map;