SpiderMonkey implemented Iterator [1][2] a while ago [3]. Apparently, no other major browser followed. ES6 is adding for..of loops (already implemented in SpiderMonkey) and the iterator protocol [4]. It seems that the risk of breaking web content is very low; web developers and Firefox developers have a good alternative, so it may be the right time to get rid of Iterator [1] https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Iterators_and_Generators [2] https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Iterator [3] https://developer.mozilla.org/en-US/docs/Web/JavaScript/New_in_JavaScript/1.7 [4] http://wiki.ecmascript.org/doku.php?id=harmony:iterators

I'm using Iterator in my Firefox app. It would be nice if Object.entries would be standardized and implemented before the non-standard Iterator is gone. https://esdiscuss.org/topic/es6-iteration-over-object-values

Posted the site compatibility doc: https://www.fxsitecompat.com/en-US/docs/2015/iterator-method-will-be-removed/

Object.entries has implemented in Bug 1208464 so we can now remove this.

Object.values and Object.entries are non-release-only.

just to update the my previous comment. Object.values/entries are now available on all branches. We should replace Iterator with them, or maybe other standard things.

Seems like Iterator was removed as part of bug 1098412.