optimise

Author: Rich-Harris

packages/svelte/src/internal/client/reactivity/effects.js

@@ -30,7 +30,8 @@ import {
 	ROOT_EFFECT,
 	EFFECT_TRANSPARENT,
 	DERIVED,
-	UNOWNED
+	UNOWNED,
+	CLEAN
 } from '../constants.js';
 import { set } from './sources.js';
 import { remove } from '../dom/reconciler.js';
@@ -68,7 +69,7 @@ export function push_effect(effect, parent_effect) {
 
 /**
  * @param {number} type
- * @param {(() => void | (() => void))} fn
+ * @param {null | (() => void | (() => void))} fn
  * @param {boolean} sync
  * @returns {import('#client').Effect}
  */
@@ -121,7 +122,7 @@ function create_effect(type, fn, sync) {
 		} finally {
 			set_is_flushing_effect(previously_flushing_effect);
 		}
-	} else {
+	} else if (fn !== null) {
 		schedule_effect(effect);
 	}
 
@@ -148,7 +149,10 @@ export function effect_active() {
  * @param {() => void} fn
  */
 export function teardown(fn) {
-	return render_effect(() => fn);
+	const effect = create_effect(RENDER_EFFECT, null, false);
+	set_signal_status(effect, CLEAN);
+	effect.teardown = fn;
+	return effect;
 }
 
 /**
@@ -371,7 +375,6 @@ export function destroy_effect(effect, remove_dom = true) {
 		effect.dom =
 		effect.deps =
 		effect.parent =
-		// @ts-expect-error
 		effect.fn =
 			null;
 }

packages/svelte/src/internal/client/reactivity/types.d.ts

@@ -18,7 +18,7 @@ export interface Value<V = unknown> extends Signal {
 
 export interface Reaction extends Signal {
 	/** The reaction function */
-	fn: Function;
+	fn: null | Function;
 	/** Signals that this signal reads from */
 	deps: null | Value[];
 	/** First child effect created inside this signal */
@@ -40,7 +40,7 @@ export interface Effect extends Reaction {
 	/** The associated component context */
 	ctx: null | ComponentContext;
 	/** The effect function */
-	fn: () => void | (() => void);
+	fn: null | (() => void) | (() => void);
 	/** The teardown function returned from the effect function */
 	teardown: null | (() => void);
 	/** Transition managers created with `$.transition` */

packages/svelte/src/internal/client/runtime.js

@@ -290,7 +290,7 @@ function handle_error(error, effect, component_context) {
 
 	const component_stack = [];
 
-	const effect_name = effect.fn.name;
+	const effect_name = effect.fn?.name;
 
 	if (effect_name) {
 		component_stack.push(effect_name);
@@ -358,7 +358,7 @@ export function execute_reaction_fn(signal) {
 	current_untracking = false;
 
 	try {
-		let res = (0, signal.fn)();
+		let res = /** @type {Function} */ (0, signal.fn)();
 		let dependencies = /** @type {import('#client').Value<unknown>[]} **/ (signal.deps);
 		if (current_dependencies !== null) {
 			let i;