is

Object.is (JavaScript)

[3] Object.is - JavaScript | MDN ( ( 版)) <https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Object/is>

[4] IRC logs: freenode / #whatwg / 20140519 ( ( 版)) <http://krijnhoetmer.nl/irc-logs/whatwg/20140519>

[5] IRC logs: freenode / #whatwg / 20150115 ( ( 版)) <http://krijnhoetmer.nl/irc-logs/whatwg/20150115>