forEach method of Node.childNodes?

Question

After providing an incorrect answer concerning the .item() property of Node.childNodes for a question, I inspected __proto__ of the returned

Answer 1

Is the method available only at relatively recent versions of Chrome / Chromium? If yes, is this documented?

Yes, this is new in DOM4, so not widely available.

Is there any documentation concerning the forEach() method of Node.childNodes?

See Add support for [ArrayClass] and use that on NodeList on the Chromium bug tracker:

From https://bugs.webkit.org/show_bug.cgi?id=81573

http://dom.spec.whatwg.org/#interface-nodelist

DOM4 specs NodeList as having Array.prototype in its prototype chain.

Some more background for this one. [ArrayClass] allows us to do things like document.querySelectorAll('.foo').forEach etc. The patch at bugs.webkit.org has a runtime flag because it is unclear if this will still be possible to achieve.

Historically these array-like objects did not include these methods from the array prototype, leading to code like Array.prototype.forEach.call(nodeList, function() { ... }). This is now meant to change in DOM4.