chore: tweak flushSync implementation (#15898)

Rich-Harris · web-flow · commit 8a351944a344 · 2025-05-12T17:07:46.000-04:00
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
@@ -828,15 +828,16 @@ export function flushSync(fn) {
 		result = fn();
 	}
 
-	flush_tasks();
+	while (true) {
+		flush_tasks();
+
+		if (queued_root_effects.length === 0) {
+			return /** @type {T} */ (result);
+		}
 
-	while (queued_root_effects.length > 0) {
 		is_flushing = true;
 		flush_queued_root_effects();
-		flush_tasks();
 	}
-
-	return /** @type {T} */ (result);
 }
 
 /**

Original file line number	Diff line number	Diff line change
`@@ -828,15 +828,16 @@ export function flushSync(fn) {`
`828`	`828`	`result = fn();`
`829`	`829`	`}`
`830`	`830`
`831`		`- flush_tasks();`
	`831`	`+ while (true) {`
	`832`	`+ flush_tasks();`
	`833`	`+`
	`834`	`+ if (queued_root_effects.length === 0) {`
	`835`	`+ return /** @type {T} */ (result);`
	`836`	`+ }`
`832`	`837`
`833`		`- while (queued_root_effects.length > 0) {`
`834`	`838`	`is_flushing = true;`
`835`	`839`	`flush_queued_root_effects();`
`836`		`- flush_tasks();`
`837`	`840`	`}`
`838`		`-`
`839`		`- return /** @type {T} */ (result);`
`840`	`841`	`}`
`841`	`842`
`842`	`843`	`/**`