WIP

packages/svelte/src/compiler/phases/3-transform/client/visitors/IfBlock.js

@@ -25,13 +25,7 @@ export function IfBlock(node, context) {
 		statements.push(b.var(alternate_id, b.arrow([b.id('$$anchor')], alternate)));
 	}
 
-	// TODO helperise
+	const is_async = node.metadata.expression.is_async();
-	const blockers = new Set();
-	for (const d of node.metadata.expression.dependencies) {
-		if (d.blocker) blockers.add(d.blocker);
-	}
-
-	const is_async = blockers.size > 0 || node.metadata.expression.has_await;
 
 	const expression = build_expression(context, node.test, node.metadata.expression);
 	const test = is_async ? b.call('$.get', b.id('$$condition')) : expression;
@@ -84,7 +78,7 @@ export function IfBlock(node, context) {
 				b.call(
 					'$.async',
 					context.state.node,
-					b.array([...blockers]),
+					node.metadata.expression.blockers(),
 					b.array([b.thunk(expression, node.metadata.expression.has_await)]),
 					b.arrow([context.state.node, b.id('$$condition')], b.block(statements))
 				)

packages/svelte/src/compiler/phases/nodes.js

@@ -1,5 +1,6 @@
 /** @import { Expression, PrivateIdentifier } from 'estree' */
 /** @import { AST, Binding } from '#compiler' */
+import * as b from '#compiler/builders';
 
 /**
  * All nodes that can appear elsewhere than the top level, have attributes and can contain children
@@ -91,6 +92,29 @@ export class ExpressionMetadata {
 	 * @type {Set<Binding>}
 	 */
 	references = new Set();
+
+	/** @type {null | Set<Expression>} */
+	#blockers = null;
+
+	#get_blockers() {
+		if (!this.#blockers) {
+			this.#blockers = new Set();
+
+			for (const d of this.dependencies) {
+				if (d.blocker) this.#blockers.add(d.blocker);
+			}
+		}
+
+		return this.#blockers;
+	}
+
+	blockers() {
+		return b.array([...this.#get_blockers()]);
+	}
+
+	is_async() {
+		return this.has_await || this.#get_blockers().size > 0;
+	}
 }
 
 export function new ExpressionMetadata() {