[DevTools] Exclude Suspense boundaries in hidden Activity #34756
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otodockal
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| function App({hidden}) { | ||
| return ( | ||
| <> | ||
| <Activity mode={hidden ? 'hidden' : 'visiible'}> |
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| <Activity mode={hidden ? 'hidden' : 'visiible'}> | |
| <Activity mode={hidden ? 'hidden' : 'visible'}> |
sebmarkbage
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Oct 7, 2025
| if (isHiddenOffscreen(fiber)) { | ||
| // hidden Activity is noisy. | ||
| // Including it may show overlapping Suspense rects | ||
| } else if (isSuspendedOffscreen(fiber)) { |
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Wouldn’t this always be false because isHiddenOffscreen above is a superset of isSuspendedOffscreen?
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Right. I handled the suspended case first in the other places but not here. Now we always handle suspended before hidden.
Though I'm not sure how to make this matter in the mount path. In the current test, fiber.child is always null when mounting a suspended Offscreen. I guess we can't hit this in modern Suspense where we don't commit an inconsistent tree. But I believe React 17 could commit an inconsistent, hidden tree where this would matter?
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Including Suspense in hidden Activity can be confusing since that likely ends up to overlapping rects (e.g. when each tab content is in an Activity or when previous "pages" are kept in Activity for a better backwards-forwards cache.
We now differentiate between Offscreen used by Suspense and Offscreen used by Activity. Activity-Offscreen will just unmount all nodes. Suspense-Offscreen will stay as-is and unmount nodes except Suspense nodes in the Suspense tree.