mdn
Clarify requirements for render-blocking
Description
Clarify requirements for render-blocking. Also make clear that we are not only blocking on fetching; also on parsing/application.
Motivation
I was caught out when trying to implement render-blocking, because I did not understand from either MDN or reading the spec that scripts with blocking="render" needed to appear in the head. This started a series of conversations with @noamr and @zcorpan about what render-blocking needs (and what needs render-blocking) which I am trying to capture in this PR.
Additional details
(see linked spec reference and Bluesky link in #39663).
I'm not sure these notes need to be in all of these places, but figured that removing them would be easier for reviewers than finding all of the places they could/should be.
Related issues and pull requests
Fixes #39663
Preview URLs (8 pages)
-
/en-US/docs/Web/API/HTMLLinkElement/blocking -
/en-US/docs/Web/API/HTMLScriptElement/blocking -
/en-US/docs/Web/API/HTMLStyleElement/blocking -
/en-US/docs/Web/API/View_Transition_API/Using -
/en-US/docs/Web/HTML/Reference/Attributes/rel -
/en-US/docs/Web/HTML/Reference/Elements/link -
/en-US/docs/Web/HTML/Reference/Elements/script -
/en-US/docs/Web/HTML/Reference/Elements/style
(comment last updated: 2025-08-04 07:08:00)
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Hi @eeeps, thanks for these updates! I've suggested a rephrasing that I hope helps to address Noam's comment. Please ping if you need any help with getting this PR over the finish line.
This pull request has merge conflicts that must be resolved before it can be merged.
@dipikabh Given it has been a month, perhaps we can move forward by applying any changes ourselves.
(Also pinging @eeeps once more for attention)
@Josh-Cena @dipikabh Thank you so much for picking this up where I left off, and apologies for the long silence. I kept thinking I would have time to get back to this "next week".
Reading through the committed changes I think they're technically correct (although @noamr is a better judge of that) but could use a little more explanation so folks understand how the various pieces here fit together.
Perhaps I'll have time to put another PR together soon. Thanks again!
Sounds good, please feel free to send a PR to add improvements/more details 🙏