HTML: Document Render-Blocking

[khushalsagar]

Request for Mozilla Position on an Emerging Web Specification

• Specification Title: HTML
• Specification or proposal URL (if available): [View Transitions] Extend render-blocking to support Document whatwg/html#9332
• Explainer URL (if available): https://github.com/WICG/view-transitions/blob/main/document-render-blocking.md
• Caniuse.com URL (optional):
• Bugzilla URL (optional):
• Mozillians who can provide input (optional): @emilio

Other information

This feature is required to support cross-document View Transitions reviewed at #677.

[vmpstr]

Hi, please note that we're proposing the following solution: https://github.com/WICG/view-transitions/blob/main/document-render-blocking.md#blocking-element-id

This is in a spec PR here: whatwg/html#9970

[zcorpan]

I think this is useful and necessary for cross-document View Transitions, as OP mentions. My main concern was about using the HTML parser end tag hook for arbitrary elements, but if whatwg/html#9332 (comment) is right then it shouldn't regress performance.

Suggest positive.

cc @hsivonen