TL;DR

SWR now includes an unload() API to manually clear cached data.

New

• unload() API (manually removes specific cache entries).

TL;DR

SWR now removes support for the downlevelIteration option, which may require code updates if you were explicitly setting this option.

Breaking

• Removed downlevelIteration option (controls older browser support).

Fixes Worth Knowing

• Fixed an issue where SWR could incorrectly unsubscribe from data updates, leading to stale data.
• Resolved a problem preventing promises from suspending correctly when data was already resolved.
• Corrected a bug related to data fetching in specific scenarios.

TL;DR

SWR now supports functional optimisticData, allowing for more dynamic and responsive UI updates when mutations occur.

New

• Functional optimisticData allows you to provide a function to calculate optimistic UI state (temporary UI state) during mutations.

Fixes Worth Knowing

• Fixed an issue where suspense and revalidateIfStale didn’t work correctly together.
• Resolved a type error in SWRConfig.

TL;DR

SWR now requires a return type when using the mutate function, improving type safety for data updates.

Breaking

• mutate function requires a return type (ensures correct data handling).

New

None.

Fixes Worth Knowing

None.

Before You Upgrade

Update your mutate calls to explicitly define a return type to avoid TypeScript errors.

TL;DR

SWR now correctly handles revalidation on focus, improving data freshness when switching between tabs or windows.

Fixes Worth Knowing

Fixed an issue where SWR would not revalidate data when a window regained focus, leading to stale data in some scenarios.

TL;DR

SWR now exposes its internal cache, allowing developers more control over data management (data storage and retrieval).

New

• Exposed Cache: Developers can now directly access and manipulate SWR’s cache for advanced use cases like pre-fetching or custom invalidation strategies.