Finish deleting Mutable from router implementation #88046
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Tests Passed |
packages/next/src/client/components/segment-cache/navigation.ts
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ztanner
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Jan 14, 2026
| const currentRenderedSearch = state.renderedSearch | ||
| const currentFlightRouterState = state.tree | ||
| const shouldScroll = true | ||
| const shouldScroll = false |
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was this an intentional behavior change?
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The net behavior is the same, it probably should have been false before but was working anyway for other reasons. There are lots of existing tests for this so I'm pretty confident it's safe.
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| export const RedirectType = { | ||
| Push: 'push', | ||
| Replace: 'replace', | ||
| } |
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I think we should keep the casing from before this refactor, eg RedirectType.push rather than RedirectType.Push so we don't break apps that were depending on this
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oh oops that was unintentional, good catch
| shouldScroll, | ||
| navigateType | ||
| ).catch(() => { | ||
| // If the navigation fails, return the current state |
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wonder if it's worth logging something during dev when this happens
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Probably should though to be clear that's the current behavior, too
| url.search === oldUrl.search && | ||
| url.hash !== oldUrl.hash | ||
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| // During a hash-only change, setting scrollableSegmeths to an empty |
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| // During a hash-only change, setting scrollableSegmeths to an empty | |
| // During a hash-only change, setting scrollableSegments to an empty |
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Jan 14, 2026
The Mutable type was used by an earlier implementation of App Router when the reducer used to run during React's render phase. It was used to prevent certain operations from running multiple times if an update was reapplied by React. Now that router "reducer" actions run outside React's render phase, we no longer need this indirection — we can compute the next state object directly. Most of the Mutable-related logic was deleted in previous PRs; this finishes the migration by inlining handleMutable into its callers.
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Based on:
The Mutable type was used by an earlier implementation of App Router when the reducer used to run during React's render phase. It was used to prevent certain operations from running multiple times if an update was reapplied by React.
Now that router "reducer" actions run outside React's render phase, we no longer need this indirection — we can compute the next state object directly.
Most of the Mutable-related logic was deleted in previous PRs; this finishes the migration by inlining handleMutable into its callers.