renderer.title

packages/svelte/src/compiler/phases/3-transform/server/visitors/TitleElement.js

@@ -14,6 +14,8 @@ export function TitleElement(node, context) {
 	template.push(b.literal('</title>'));
 
 	context.state.init.push(
-		b.stmt(b.call('$.build_title', b.id('$$renderer'), b.thunk(b.block(build_template(template)))))
+		b.stmt(
+			b.call('$$renderer.title', b.arrow([b.id('$$renderer')], b.block(build_template(template))))
+		)
 	);
 }

packages/svelte/src/internal/server/index.js

@@ -493,32 +493,3 @@ export function derived(fn) {
 		return updated_value;
 	};
 }
-
-/**
- * Since your document can only have one `title`, we have to have some sort of algorithm for determining
- * which one "wins". To do this, we perform a depth-first comparison of where the title was encountered --
- * later ones "win" over earlier ones, regardless of what order the promises resolve in. To accomodate this, we:
- * - Figure out where we are in the content tree (`get_path`)
- * - Render the title in its own child so that it has a defined "slot" in the renderer
- * - Compact that spot so that we get the entire rendered contents of the title
- * - Attempt to set the global title (this is where the "wins" logic based on the path happens)
- *
- * TODO we could optimize this by not even rendering the title if the path wouldn't be accepted
- *
- * @param {Renderer} renderer
- * @param {((renderer: Renderer) => void | Promise<void>)} children
- */
-export function build_title(renderer, children) {
-	const path = renderer.get_path();
-	const i = renderer.length;
-	renderer.child(children);
-	renderer.compact({
-		start: i,
-		fn: ({ head }) => {
-			renderer.global.set_title(head, path);
-			// since we can only ever render the title in this chunk, and title rendering is handled specially,
-			// we can just ditch the results after we've saved them globally
-			return { head: '', body: '' };
-		}
-	});
-}

packages/svelte/src/internal/server/renderer.js

@@ -222,6 +222,34 @@ export class Renderer {
 		}
 	}
 
+	/**
+	 * @param {(renderer: Renderer) => void} fn
+	 */
+	title(fn) {
+		const path = this.get_path();
+
+		/** @param {string} head */
+		const close = (head) => {
+			this.global.set_title(head, path);
+		};
+
+		this.child((renderer) => {
+			const r = new Renderer(renderer.global, renderer);
+			fn(r);
+
+			const content = { head: '', body: '' };
+
+			if (renderer.global.mode === 'async') {
+				return Renderer.#collect_content_async([r], 'body', content).then(() => {
+					close(content.head);
+				});
+			} else {
+				Renderer.#collect_content([r], 'body', content);
+				close(content.head);
+			}
+		});
+	}
+
 	/**
 	 * @param {string | (() => Promise<string>)} content
 	 */