Merge branch 'main' into developer-guide

paoloricciuti · paoloricciuti · commit 425e68ac6c4a · 2025-08-17T20:52:31.000+02:00
diff --git a/.changeset/clever-months-clap.md b/.changeset/clever-months-clap.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+perf: run blocks eagerly during flush instead of aborting
diff --git a/.changeset/few-geese-itch.md b/.changeset/few-geese-itch.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: destroy dynamic component instance before creating new one
diff --git a/.changeset/itchy-games-guess.md b/.changeset/itchy-games-guess.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: don't clone non-proxies in `$inspect`
diff --git a/.changeset/six-shirts-scream.md b/.changeset/six-shirts-scream.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: avoid recursion error when tagging circular references
diff --git a/packages/svelte/src/internal/client/dev/inspect.js b/packages/svelte/src/internal/client/dev/inspect.js
@@ -26,7 +26,7 @@ export function inspect(get_value, inspector = console.log) {
 			return;
 		}
 
-		var snap = snapshot(value, true);
+		var snap = snapshot(value, true, true);
 		untrack(() => {
 			inspector(initial ? 'init' : 'update', ...snap);
 		});
diff --git a/packages/svelte/src/internal/client/dom/blocks/svelte-component.js b/packages/svelte/src/internal/client/dom/blocks/svelte-component.js
@@ -34,11 +34,6 @@ export function component(node, get_component, render_fn) {
 	var pending_effect = null;
 
 	function commit() {
-		if (effect) {
-			pause_effect(effect);
-			effect = null;
-		}
-
 		if (offscreen_fragment) {
 			// remove the anchor
 			/** @type {Text} */ (offscreen_fragment.lastChild).remove();
@@ -56,6 +51,11 @@ export function component(node, get_component, render_fn) {
 
 		var defer = should_defer_append();
 
+		if (effect) {
+			pause_effect(effect);
+			effect = null;
+		}
+
 		if (component) {
 			var target = anchor;
 
diff --git a/packages/svelte/src/internal/client/dom/operations.js b/packages/svelte/src/internal/client/dom/operations.js
@@ -6,6 +6,7 @@ import { get_descriptor, is_extensible } from '../../shared/utils.js';
 import { active_effect } from '../runtime.js';
 import { async_mode_flag } from '../../flags/index.js';
 import { TEXT_NODE, EFFECT_RAN } from '#client/constants';
+import { eager_block_effects } from '../reactivity/batch.js';
 
 // export these for reference in the compiled code, making global name deduplication unnecessary
 /** @type {Window} */
@@ -214,6 +215,7 @@ export function clear_text_content(node) {
  */
 export function should_defer_append() {
 	if (!async_mode_flag) return false;
+	if (eager_block_effects !== null) return false;
 
 	var flags = /** @type {Effect} */ (active_effect).f;
 	return (flags & EFFECT_RAN) !== 0;
diff --git a/packages/svelte/src/internal/client/proxy.js b/packages/svelte/src/internal/client/proxy.js
@@ -93,9 +93,11 @@ export function proxy(value) {
 
 	/** Used in dev for $inspect.trace() */
 	var path = '';
-
+	let updating = false;
 	/** @param {string} new_path */
 	function update_path(new_path) {
+		if (updating) return;
+		updating = true;
 		path = new_path;
 
 		tag(version, `${path} version`);
@@ -104,6 +106,7 @@ export function proxy(value) {
 		for (const [prop, source] of sources) {
 			tag(source, get_label(path, prop));
 		}
+		updating = false;
 	}
 
 	return new Proxy(/** @type {any} */ (value), {
@@ -284,13 +287,13 @@ export function proxy(value) {
 			if (s === undefined) {
 				if (!has || get_descriptor(target, prop)?.writable) {
 					s = with_parent(() => source(undefined, stack));
-					set(s, proxy(value));
-
-					sources.set(prop, s);
 
 					if (DEV) {
 						tag(s, get_label(path, prop));
 					}
+					set(s, proxy(value));
+
+					sources.set(prop, s);
 				}
 			} else {
 				has = s.v !== UNINITIALIZED;
diff --git a/packages/svelte/src/internal/client/reactivity/batch.js b/packages/svelte/src/internal/client/reactivity/batch.js
@@ -292,12 +292,12 @@ export class Batch {
 			if (!skip && effect.fn !== null) {
 				if (is_branch) {
 					effect.f ^= CLEAN;
+				} else if ((flags & EFFECT) !== 0) {
+					this.#effects.push(effect);
+				} else if (async_mode_flag && (flags & RENDER_EFFECT) !== 0) {
+					this.#render_effects.push(effect);
 				} else if ((flags & CLEAN) === 0) {
-					if ((flags & EFFECT) !== 0) {
-						this.#effects.push(effect);
-					} else if (async_mode_flag && (flags & RENDER_EFFECT) !== 0) {
-						this.#render_effects.push(effect);
-					} else if ((flags & ASYNC) !== 0) {
+					if ((flags & ASYNC) !== 0) {
 						var effects = effect.b?.pending ? this.#boundary_async_effects : this.#async_effects;
 						effects.push(effect);
 					} else if (is_dirty(effect)) {
@@ -584,6 +584,9 @@ function infinite_loop_guard() {
 	}
 }
 
+/** @type {Effect[] | null} */
+export let eager_block_effects = null;
+
 /**
  * @param {Array<Effect>} effects
  * @returns {void}
@@ -598,7 +601,7 @@ function flush_queued_effects(effects) {
 		var effect = effects[i++];
 
 		if ((effect.f & (DESTROYED | INERT)) === 0 && is_dirty(effect)) {
-			var n = current_batch ? current_batch.current.size : 0;
+			eager_block_effects = [];
 
 			update_effect(effect);
 
@@ -619,21 +622,20 @@ function flush_queued_effects(effects) {
 				}
 			}
 
-			// if state is written in a user effect, abort and re-schedule, lest we run
-			// effects that should be removed as a result of the state change
-			if (
-				current_batch !== null &&
-				current_batch.current.size > n &&
-				(effect.f & USER_EFFECT) !== 0
-			) {
-				break;
+			if (eager_block_effects.length > 0) {
+				// TODO this feels incorrect! it gets the tests passing
+				old_values.clear();
+
+				for (const e of eager_block_effects) {
+					update_effect(e);
+				}
+
+				eager_block_effects = [];
 			}
 		}
 	}
 
-	while (i < length) {
-		schedule_effect(effects[i++]);
-	}
+	eager_block_effects = null;
 }
 
 /**
diff --git a/packages/svelte/src/internal/client/reactivity/sources.js b/packages/svelte/src/internal/client/reactivity/sources.js
@@ -33,7 +33,7 @@ import * as e from '../errors.js';
 import { legacy_mode_flag, tracing_mode_flag } from '../../flags/index.js';
 import { get_stack, tag_proxy } from '../dev/tracing.js';
 import { component_context, is_runes } from '../context.js';
-import { Batch, schedule_effect } from './batch.js';
+import { Batch, eager_block_effects, schedule_effect } from './batch.js';
 import { proxy } from '../proxy.js';
 import { execute_derived } from './deriveds.js';
 
@@ -334,6 +334,12 @@ function mark_reactions(signal, status) {
 		if ((flags & DERIVED) !== 0) {
 			mark_reactions(/** @type {Derived} */ (reaction), MAYBE_DIRTY);
 		} else if (not_dirty) {
+			if ((flags & BLOCK_EFFECT) !== 0) {
+				if (eager_block_effects !== null) {
+					eager_block_effects.push(/** @type {Effect} */ (reaction));
+				}
+			}
+
 			schedule_effect(/** @type {Effect} */ (reaction));
 		}
 	}
diff --git a/packages/svelte/src/internal/shared/clone.js b/packages/svelte/src/internal/shared/clone.js
@@ -15,14 +15,15 @@ const empty = [];
  * @template T
  * @param {T} value
  * @param {boolean} [skip_warning]
+ * @param {boolean} [no_tojson]
  * @returns {Snapshot<T>}
  */
-export function snapshot(value, skip_warning = false) {
+export function snapshot(value, skip_warning = false, no_tojson = false) {
 	if (DEV && !skip_warning) {
 		/** @type {string[]} */
 		const paths = [];
 
-		const copy = clone(value, new Map(), '', paths);
+		const copy = clone(value, new Map(), '', paths, null, no_tojson);
 		if (paths.length === 1 && paths[0] === '') {
 			// value could not be cloned
 			w.state_snapshot_uncloneable();
@@ -40,7 +41,7 @@ export function snapshot(value, skip_warning = false) {
 		return copy;
 	}
 
-	return clone(value, new Map(), '', empty);
+	return clone(value, new Map(), '', empty, null, no_tojson);
 }
 
 /**
@@ -49,10 +50,11 @@ export function snapshot(value, skip_warning = false) {
  * @param {Map<T, Snapshot<T>>} cloned
  * @param {string} path
  * @param {string[]} paths
- * @param {null | T} original The original value, if `value` was produced from a `toJSON` call
+ * @param {null | T} [original] The original value, if `value` was produced from a `toJSON` call
+ * @param {boolean} [no_tojson]
  * @returns {Snapshot<T>}
  */
-function clone(value, cloned, path, paths, original = null) {
+function clone(value, cloned, path, paths, original = null, no_tojson = false) {
 	if (typeof value === 'object' && value !== null) {
 		var unwrapped = cloned.get(value);
 		if (unwrapped !== undefined) return unwrapped;
@@ -71,7 +73,7 @@ function clone(value, cloned, path, paths, original = null) {
 			for (var i = 0; i < value.length; i += 1) {
 				var element = value[i];
 				if (i in value) {
-					copy[i] = clone(element, cloned, DEV ? `${path}[${i}]` : path, paths);
+					copy[i] = clone(element, cloned, DEV ? `${path}[${i}]` : path, paths, null, no_tojson);
 				}
 			}
 
@@ -88,8 +90,15 @@ function clone(value, cloned, path, paths, original = null) {
 			}
 
 			for (var key in value) {
-				// @ts-expect-error
-				copy[key] = clone(value[key], cloned, DEV ? `${path}.${key}` : path, paths);
+				copy[key] = clone(
+					// @ts-expect-error
+					value[key],
+					cloned,
+					DEV ? `${path}.${key}` : path,
+					paths,
+					null,
+					no_tojson
+				);
 			}
 
 			return copy;
@@ -99,7 +108,7 @@ function clone(value, cloned, path, paths, original = null) {
 			return /** @type {Snapshot<T>} */ (structuredClone(value));
 		}
 
-		if (typeof (/** @type {T & { toJSON?: any } } */ (value).toJSON) === 'function') {
+		if (typeof (/** @type {T & { toJSON?: any } } */ (value).toJSON) === 'function' && !no_tojson) {
 			return clone(
 				/** @type {T & { toJSON(): any } } */ (value).toJSON(),
 				cloned,
diff --git a/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/A.svelte b/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/A.svelte
@@ -0,0 +1,8 @@
+<script>
+	$effect.pre(() => {
+		console.log('create A');
+		return () => console.log('destroy A');
+	});
+</script>
+
+<h1>A</h1>
diff --git a/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/B.svelte b/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/B.svelte
@@ -0,0 +1,8 @@
+<script>
+	$effect.pre(() => {
+		console.log('create B');
+		return () => console.log('destroy B');
+	});
+</script>
+
+<h1>B</h1>
diff --git a/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/_config.js b/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/_config.js
@@ -0,0 +1,13 @@
+import { test } from '../../test';
+import { flushSync } from 'svelte';
+
+export default test({
+	mode: ['client', 'hydrate'],
+
+	async test({ assert, target, logs }) {
+		const [button] = target.querySelectorAll('button');
+
+		flushSync(() => button.click());
+		assert.deepEqual(logs, ['create A', 'destroy A', 'create B']);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/main.svelte b/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/main.svelte
@@ -0,0 +1,13 @@
+<script>
+	import A from './A.svelte';
+	import B from './B.svelte';
+
+	let condition = $state(true);
+	let Component = $derived(condition ? A : B);
+</script>
+
+<button onclick={() => condition = !condition}>
+	toggle ({condition})
+</button>
+
+<Component />
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-loop-3/Child.svelte b/packages/svelte/tests/runtime-runes/samples/effect-loop-3/Child.svelte
@@ -0,0 +1,13 @@
+<script>
+	let { children } = $props();
+
+	let inited = $state(false);
+
+	$effect(() => {
+		inited = true;
+	});
+</script>
+
+{#if inited}
+	<span>{@render children()}</span>
+{/if}
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-loop-3/_config.js b/packages/svelte/tests/runtime-runes/samples/effect-loop-3/_config.js
@@ -0,0 +1,12 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target }) {
+		const [button] = target.querySelectorAll('button');
+
+		assert.doesNotThrow(() => {
+			flushSync(() => button.click());
+		});
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-loop-3/main.svelte b/packages/svelte/tests/runtime-runes/samples/effect-loop-3/main.svelte
@@ -0,0 +1,15 @@
+<script>
+	import Child from './Child.svelte';
+
+	let show = $state(false);
+</script>
+
+<button onclick={() => show = !show}>
+	toggle
+</button>
+
+{#if show}
+	{#each { length: 1234 } as i}
+		<Child>{i}</Child>
+	{/each}
+{/if}
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-6/A.svelte b/packages/svelte/tests/runtime-runes/samples/effect-order-6/A.svelte
@@ -1,11 +1,12 @@
 <script>
 	import B from './B.svelte';
 
-	let { boolean, closed } = $props();
+	let { boolean, closed, close } = $props();
 
+	// this runs after the effect in B, because child effects run first
 	$effect(() => {
-		console.log(boolean);
+		console.log({ boolean, closed });
 	});
 </script>
 
-<B {closed} />
+<B {closed} {close} />
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-6/B.svelte b/packages/svelte/tests/runtime-runes/samples/effect-order-6/B.svelte
@@ -1,7 +1,5 @@
 <script>
-	import { close } from './Child.svelte';
-
-	let { closed } = $props();
+	let { closed, close } = $props();
 
 	$effect(() => {
 		if (closed) close();
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-6/Child.svelte b/packages/svelte/tests/runtime-runes/samples/effect-order-6/Child.svelte
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-6/_config.js b/packages/svelte/tests/runtime-runes/samples/effect-order-6/_config.js
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-6/main.svelte b/packages/svelte/tests/runtime-runes/samples/effect-order-6/main.svelte
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-7/A.svelte b/packages/svelte/tests/runtime-runes/samples/effect-order-7/A.svelte
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-7/B.svelte b/packages/svelte/tests/runtime-runes/samples/effect-order-7/B.svelte
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-7/Child.svelte b/packages/svelte/tests/runtime-runes/samples/effect-order-7/Child.svelte
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-7/main.svelte b/packages/svelte/tests/runtime-runes/samples/effect-order-7/main.svelte
diff --git a/packages/svelte/tests/runtime-runes/samples/inspect-recursive-2/main.svelte b/packages/svelte/tests/runtime-runes/samples/inspect-recursive-2/main.svelte
diff --git a/packages/svelte/tests/runtime-runes/samples/inspect-trace-circular-reference/_config.js b/packages/svelte/tests/runtime-runes/samples/inspect-trace-circular-reference/_config.js
diff --git a/packages/svelte/tests/runtime-runes/samples/inspect-trace-circular-reference/main.svelte b/packages/svelte/tests/runtime-runes/samples/inspect-trace-circular-reference/main.svelte

-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +---
 +'svelte': patch
 +---
++
 +perf: run blocks eagerly during flush instead of aborting
Original file line number	Diff line number	Diff line change
`@@ -26,7 +26,7 @@ export function inspect(get_value, inspector = console.log) {`
`26`	`26`	`return;`
`27`	`27`	`}`
`28`	`28`
`29`		`- var snap = snapshot(value, true);`
	`29`	`+ var snap = snapshot(value, true, true);`
`30`	`30`	`untrack(() => {`
`31`	`31`	`inspector(initial ? 'init' : 'update', ...snap);`
`32`	`32`	`});`