chore: simplify code (#10294)

* chore: simplify code

* a few more

* constify

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>

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

@@ -1420,13 +1420,10 @@ export function user_effect(init) {
 		!apply_component_effect_heuristics
 	);
 	if (apply_component_effect_heuristics) {
-		let effects = /** @type {import('./types.js').ComponentContext} */ (current_component_context)
-			.e;
-		if (effects === null) {
-			effects = /** @type {import('./types.js').ComponentContext} */ (current_component_context).e =
-				[];
-		}
-		effects.push(effect);
+		const context = /** @type {import('./types.js').ComponentContext} */ (
+			current_component_context
+		);
+		(context.e ??= []).push(effect);
 	}
 	return effect;
 }
@@ -1744,12 +1741,7 @@ export function get_or_init_context_map() {
 				(DEV ? 'Context can only be used during component initialisation.' : '')
 		);
 	}
-	let context_map = component_context.c;
-	if (context_map === null) {
-		const parent_context = get_parent_context(component_context);
-		context_map = component_context.c = new Map(parent_context || undefined);
-	}
-	return context_map;
+	return (component_context.c ??= new Map(get_parent_context(component_context) || undefined));
 }
 
 /**

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

@@ -683,10 +683,7 @@ function if_block_transition(transition) {
 	const block = this;
 	// block.value === true
 	if (block.v) {
-		let consequent_transitions = block.c;
-		if (consequent_transitions === null) {
-			consequent_transitions = block.c = new Set();
-		}
+		const consequent_transitions = (block.c ??= new Set());
 		consequent_transitions.add(transition);
 		transition.f(() => {
 			const c = /** @type {Set<import('./types.js').Transition>} */ (consequent_transitions);
@@ -697,10 +694,7 @@ function if_block_transition(transition) {
 			}
 		});
 	} else {
-		let alternate_transitions = block.a;
-		if (alternate_transitions === null) {
-			alternate_transitions = block.a = new Set();
-		}
+		const alternate_transitions = (block.a ??= new Set());
 		alternate_transitions.add(transition);
 		transition.f(() => {
 			const a = /** @type {Set<import('./types.js').Transition>} */ (alternate_transitions);
@@ -732,25 +726,20 @@ function each_item_transition(transition) {
 	if (transition.r === 'key' && (each_block.f & EACH_IS_ANIMATED) === 0) {
 		each_block.f |= EACH_IS_ANIMATED;
 	}
-	let transitions = block.s;
-	if (transitions === null) {
-		block.s = transitions = new Set();
-	}
+	const transitions = (block.s ??= new Set());
 	transition.f(() => {
-		if (transitions !== null) {
-			transitions.delete(transition);
-			if (transition.r !== 'key') {
-				for (let other of transitions) {
-					const type = other.r;
-					if (type === 'key' || type === 'in') {
-						transitions.delete(other);
-					}
-				}
-				if (transitions.size === 0) {
-					block.s = null;
-					destroy_each_item_block(block, null, true);
+		transitions.delete(transition);
+		if (transition.r !== 'key') {
+			for (let other of transitions) {
+				const type = other.r;
+				if (type === 'key' || type === 'in') {
+					transitions.delete(other);
 				}
 			}
+			if (transitions.size === 0) {
+				block.s = null;
+				destroy_each_item_block(block, null, true);
+			}
 		}
 	});
 	transitions.add(transition);

packages/svelte/src/main/main-client.js

@@ -215,10 +215,7 @@ export function beforeUpdate(fn) {
 		throw new Error('beforeUpdate can only be used during component initialisation.');
 	}
 
-	if (component_context.u === null) {
-		component_context.u = init_update_callbacks();
-	}
-	component_context.u.b.push(fn);
+	(component_context.u ??= init_update_callbacks()).b.push(fn);
 }
 
 /**
@@ -239,10 +236,7 @@ export function afterUpdate(fn) {
 		throw new Error('afterUpdate can only be used during component initialisation.');
 	}
 
-	if (component_context.u === null) {
-		component_context.u = init_update_callbacks();
-	}
-	component_context.u.a.push(fn);
+	(component_context.u ??= init_update_callbacks()).a.push(fn);
 }
 
 // TODO bring implementations in here