address feedback

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

@@ -9,31 +9,44 @@ import * as b from '../../../../utils/builders.js';
  */
 export function IfBlock(node, context) {
 	context.state.template.push('<!>');
+	const statements = [];
 
 	const consequent = /** @type {BlockStatement} */ (context.visit(node.consequent));
 	const consequent_id = context.state.scope.generate('consequent');
 
-	context.state.init.push(b.var(b.id(consequent_id), b.arrow([b.id('$$anchor')], consequent)));
+	statements.push(b.var(b.id(consequent_id), b.arrow([b.id('$$anchor')], consequent)));
 
 	let alternate_id;
 
 	if (node.alternate) {
 		const alternate = /** @type {BlockStatement} */ (context.visit(node.alternate));
 		alternate_id = context.state.scope.generate('alternate');
-		context.state.init.push(b.var(b.id(alternate_id), b.arrow([b.id('$$anchor')], alternate)));
+		statements.push(b.var(b.id(alternate_id), b.arrow([b.id('$$anchor')], alternate)));
 	}
 
 	/** @type {Expression[]} */
 	const args = [
 		context.state.node,
 		b.arrow(
-			[b.id('$$branch')],
+			[b.id('$$render')],
 			b.block([
 				b.if(
 					/** @type {Expression} */ (context.visit(node.test)),
-					b.stmt(b.call(b.id('$$branch'), b.literal(0), b.id(consequent_id))),
+					b.stmt(
+						b.call(
+							b.id('$$render'),
+							b.id(consequent_id),
+							node.alternate ? b.literal(true) : undefined
+						)
+					),
 					alternate_id
-						? b.stmt(b.call(b.id('$$branch'), b.literal(1), b.id(alternate_id)))
+						? b.stmt(
+								b.call(
+									b.id('$$render'),
+									b.id(alternate_id),
+									node.alternate ? b.literal(false) : undefined
+								)
+							)
 						: undefined
 				)
 			])
@@ -65,5 +78,7 @@ export function IfBlock(node, context) {
 		args.push(b.literal(true));
 	}
 
-	context.state.init.push(b.stmt(b.call('$.if', ...args)));
+	statements.push(b.stmt(b.call('$.if', ...args)));
+
+	context.state.init.push(b.block(statements));
 }

packages/svelte/src/internal/client/dom/blocks/if.js

@@ -13,7 +13,7 @@ import { HYDRATION_START_ELSE } from '../../../../constants.js';
 
 /**
  * @param {TemplateNode} node
- * @param {(branch: (flag: 0 | 1, fn: (anchor: Node) => void) => void) => void} fn
+ * @param {(branch: (fn: (anchor: Node) => void, flag?: boolean) => void) => void} fn
  * @param {boolean} [elseif] True if this is an `{:else if ...}` block rather than an `{#if ...}`, as that affects which transitions are considered 'local'
  * @returns {void}
  */
@@ -37,9 +37,9 @@ export function if_block(node, fn, elseif = false) {
 
 	var has_branch = false;
 
-	const set_branch = (/** @type {0 | 1} */ flag, /** @type {(anchor: Node) => void} */ fn) => {
+	const set_branch = (/** @type {(anchor: Node) => void} */ fn, flag = true) => {
 		has_branch = true;
-		update_branch(flag === 0, fn);
+		update_branch(flag, fn);
 	};
 
 	const update_branch = (