Copyright (c) Mozilla Foundation http://www.mozilla.org/
This code is available under the terms of the MIT License

https://developer.mozilla.org/ja/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach
https://developer.mozilla.org/ja/docs/Web/JavaScript/Reference/Global_Objects/Array/map
https://developer.mozilla.org/ja/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce
https://developer.mozilla.org/ja/docs/Web/JavaScript/Reference/Global_Objects/Array/filter
https://developer.mozilla.org/ja/docs/Web/JavaScript/Reference/Global_Objects/Object/keys

