(fix) keepPreviousData: return fallback instead of undefined value (#…

…4087) Co-authored-by: Jiachi Liu <[email protected]>
vercel · Feb 5, 2025 · 1d269f6 · 1d269f6
1 parent 42c05f1
commit 1d269f6
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/src/index/use-swr.ts b/src/index/use-swr.ts
@@ -278,7 +278,10 @@ export const useSWRHandler = <Data = any, Error = any>(
 
   const returnedData = keepPreviousData
     ? isUndefined(cachedData)
-      ? laggyDataRef.current ?? data
+      // checking undefined to avoid null being fallback as well
+      ? isUndefined(laggyDataRef.current)
+        ? data
+        : laggyDataRef.current
       : cachedData
     : data