HTMLCollection

DOM dom

Baseline: Widely available on the web, in every major browser since Jul 2015, and long enough to count on (since Jan 2018).

niso: No WPT tests. WPT maps no test to it. WPT results recorded at f3b4fa8, 2026-11-10; web-features 3.45.0. WPT tests · niso's support · Attr, CDATASection, CharacterData, Comment

HTMLCollection is an interface in idl/dom.webidl, exposed in Window. What it does is on MDN; this page says what niso has of it.

Status

The web features its members belong to, each with its Baseline status on the web and how much of the feature’s WPT suite passes in niso (see Web platform support).

Feature	On the web	In niso	Members
DOM	Widely available	No WPT tests WPT maps no test to it	2

Members

item()

operation

getter Element? item(unsigned long index);

Not in niso yet

Members the web has, by the BCD keys web-features 3.45.0 lists, that idl/ doesn’t declare. The list is partial: web-features lists only the keys it maps to a feature.

• length (DOM)
• namedItem (DOM)