fix: Avoid unnecessary startTransition on cached popstate navigations

Ala-Ben-Aissia · Ala-Ben-Aissia · commit 62b0edd3cd56 · 2025-08-19T12:31:48.000+01:00
diff --git a/exercises/04.router/05.solution.cache/ui/index.js b/exercises/04.router/05.solution.cache/ui/index.js
@@ -56,9 +56,10 @@ function Root() {
 				const fetchPromise = fetchContent(nextLocation)
 				const nextContentPromise = createFromFetch(fetchPromise)
 				contentCache.set(historyKey, nextContentPromise)
+				startTransition(() => setContentKey(historyKey))
+			} else {
+				setContentKey(historyKey)
 			}
-
-			startTransition(() => setContentKey(historyKey))
 		}
 		window.addEventListener('popstate', handlePopState)
 		return () => window.removeEventListener('popstate', handlePopState)

Original file line number	Diff line number	Diff line change
`@@ -56,9 +56,10 @@ function Root() {`
`56`	`56`	`const fetchPromise = fetchContent(nextLocation)`
`57`	`57`	`const nextContentPromise = createFromFetch(fetchPromise)`
`58`	`58`	`contentCache.set(historyKey, nextContentPromise)`
	`59`	`+ startTransition(() => setContentKey(historyKey))`
	`60`	`+ } else {`
	`61`	`+ setContentKey(historyKey)`
`59`	`62`	`}`
`60`		`-`
`61`		`- startTransition(() => setContentKey(historyKey))`
`62`	`63`	`}`
`63`	`64`	`window.addEventListener('popstate', handlePopState)`
`64`	`65`	`return () => window.removeEventListener('popstate', handlePopState)`