How we built it

Custom Elements v1

Custom Elements let web authors define their own tags. Chrome shipped an implementation based on the working draft of the spec in M33. The current editor's draft of the spec has significant updates based on web developer and implementer feedback.


Safari has indicated that they will not implement customized built-in elements, eg



Working draft or equivalent

Status in Chromium

Enabled by default (launch bug) in:

  • Chrome for desktop release 54
  • Chrome for Android release 54
  • Android WebView release 54
  • Opera release 41
  • Opera for Android release 41

Consensus & Standardization


Last updated on 2016-08-31