[3] Object.is - JavaScript | MDN ( (2013-03-30 14:57:36 +09:00 版)) https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Object/is

[4] IRC logs: freenode / #whatwg / 20140519 ( (2014-05-22 17:23:00 +09:00 版)) http://krijnhoetmer.nl/irc-logs/whatwg/20140519

[5] IRC logs: freenode / #whatwg / 20150115 ( (2015-01-16 11:42:14 +09:00 版)) http://krijnhoetmer.nl/irc-logs/whatwg/20150115