Allow deferring same-origin cross-document commit

[noamr]

Deferred same-origin cross-document commit

This gives a way for authors to defer a same-origin cross-document navigation commit.

The API is used in this way:

// It's called "deferPageSwap" rather than "deferCommit"
// because it does "commit" a same-document navigation.
navigateEvent.deferPageSwap({
  // This means that the history is swapped immediately, like a `pushState`,
  // and the navigation becomes a `replace`.
  historyChange: "immediate",
  async handler(controller) {
     const transition = document.startViewTransition(show_skeleton);

     // The restore callback will be called if the navigation is aborted, or if this document is restored from BFCache.
     controller.addRestoreCallback(() => hide_skeleton());
     return transition.finished;
  }
});

See explainer.
Closes #11819

• At least two implementers are interested (and none opposed):
  • …
  • …
• Tests are written and can be reviewed and commented upon at:
  • …
• Implementation bugs are filed:
  • Chromium: …
  • Gecko: …
  • WebKit: …
  • Deno (only for timers, structured clone, base64 utils, channel messaging, module resolution, web workers, and web storage): …
  • Node.js (only for timers, structured clone, base64 utils, channel messaging, and module resolution): …
• Corresponding HTML AAM & ARIA in HTML issues & PRs:
• MDN issue is filed: …
• The top of this comment includes a clear commit message to use.

(See WHATWG Working Mode: Changes for more details.)

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/browsing-the-web.html ( diff )
/index.html ( diff )
/nav-history-apis.html ( diff )