chore: avoid microtasks when flushing sync (alternative) (#15895)

Rich-Harris · trueadm · web-flow · commit b6164128b3ea · 2025-05-12T15:51:05.000-04:00
* chore: avoid microtasks when flushing sync * chore: avoid microtasks when flushing sync * chore: avoid microtasks when flushing sync * tweak * WIP * another * more * tweak * fix * fix * belt and braces * Revert "belt and braces" This reverts commit f8de1cf. --------- Co-authored-by: Dominic Gannaway <trueadm@users.noreply.github.com>
diff --git a/.changeset/polite-melons-tickle.md b/.changeset/polite-melons-tickle.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+chore: avoid microtasks when flushing sync
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
@@ -823,6 +823,8 @@ export function flushSync(fn) {
 	if (fn) {
 		is_flushing = true;
 		flush_queued_root_effects();
+
+		is_flushing = true;
 		result = fn();
 	}
 

-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +---
 +'svelte': patch
 +---
++
 +chore: avoid microtasks when flushing sync
Original file line number	Diff line number	Diff line change
`@@ -823,6 +823,8 @@ export function flushSync(fn) {`
`823`	`823`	`if (fn) {`
`824`	`824`	`is_flushing = true;`
`825`	`825`	`flush_queued_root_effects();`
	`826`	`+`
	`827`	`+ is_flushing = true;`
`826`	`828`	`result = fn();`
`827`	`829`	`}`
`828`	`830`