fix: avoid running load functions when prerendering if no server load function exists and SSR is off (#11405)

teemingc · web-flow · commit b999cfdea24e · 2023-12-21T08:28:58.000-08:00
diff --git a/.changeset/orange-students-hide.md b/.changeset/orange-students-hide.md
@@ -0,0 +1,5 @@
+---
+"@sveltejs/kit": patch
+---
+
+fix: render SPA shell when SSR is turned off and there is no server data
diff --git a/packages/kit/src/runtime/server/page/index.js b/packages/kit/src/runtime/server/page/index.js
@@ -72,7 +72,7 @@ export async function render_page(event, page, options, manifest, state, resolve
 			}
 		}
 
-		const should_prerender_data = nodes.some((node) => node?.server);
+		const should_prerender_data = nodes.some((node) => node?.server?.load);
 		const data_pathname = add_data_suffix(event.url.pathname);
 
 		// it's crucial that we do this before returning the non-SSR response, otherwise
@@ -98,7 +98,10 @@ export async function render_page(event, page, options, manifest, state, resolve
 		/** @type {import('./types.js').Fetched[]} */
 		const fetched = [];
 
-		if (get_option(nodes, 'ssr') === false && !state.prerendering) {
+		// renders an empty 'shell' page if SSR is turned off and if there is
+		// no server data to prerender. As a result, the load functions and rendering
+		// only occur client-side.
+		if (get_option(nodes, 'ssr') === false && !(state.prerendering && should_prerender_data)) {
 			return await render_response({
 				branch: [],
 				fetched,
@@ -281,6 +284,8 @@ export async function render_page(event, page, options, manifest, state, resolve
 			});
 		}
 
+		const ssr = get_option(nodes, 'ssr') ?? true;
+
 		return await render_response({
 			event,
 			options,
@@ -289,11 +294,11 @@ export async function render_page(event, page, options, manifest, state, resolve
 			resolve_opts,
 			page_config: {
 				csr: get_option(nodes, 'csr') ?? true,
-				ssr: get_option(nodes, 'ssr') ?? true
+				ssr
 			},
 			status,
 			error: null,
-			branch: compact(branch),
+			branch: ssr === false ? [] : compact(branch),
 			action_result,
 			fetched
 		});
diff --git a/packages/kit/test/prerendering/basics/src/routes/spa-shell/+page.js b/packages/kit/test/prerendering/basics/src/routes/spa-shell/+page.js
@@ -0,0 +1,10 @@
+import { redirect } from '@sveltejs/kit';
+
+export const prerender = true;
+
+export const ssr = false;
+
+/** @type {import('@sveltejs/kit').Load} */
+export function load() {
+	redirect(301, 'https://example.com/redirected');
+}
diff --git a/packages/kit/test/prerendering/basics/src/routes/spa-shell/+page.server.js b/packages/kit/test/prerendering/basics/src/routes/spa-shell/+page.server.js
@@ -0,0 +1 @@
+// spa shell should still prererender when +page.server.js exists but it has no load function
diff --git a/packages/kit/test/prerendering/basics/src/routes/spa-shell/+page.svelte b/packages/kit/test/prerendering/basics/src/routes/spa-shell/+page.svelte
@@ -0,0 +1 @@
+<h1>this won't be prerendered</h1>
diff --git a/packages/kit/test/prerendering/basics/test/tests.spec.js b/packages/kit/test/prerendering/basics/test/tests.spec.js
@@ -60,6 +60,14 @@ test('renders a relative redirect', () => {
 	);
 });
 
+test('renders a shell when SSR is turned off and there is no server data', () => {
+	const content = read('spa-shell.html');
+	assert.match(
+		content,
+		/<!doctype html>\n<html lang="en">([\s]*?)<head>([\s]*?)<meta charset="utf-8" \/>([\s]*?)<meta name="viewport" content="width=device-width, initial-scale=1" \/>([\s\S]*?)<\/head>\n([\s]*?)<body>([\s]*?)<script>([\s\S]*?)<\/script>([\s]*?)<\/body>\n<\/html>/g
+	);
+});
+
 test('inserts http-equiv tag for cache-control headers', () => {
 	const content = read('max-age.html');
 	expect(content).toMatch('<meta http-equiv="cache-control" content="max-age=300">');

-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +---
 +"@sveltejs/kit": patch
 +---
++
 +fix: render SPA shell when SSR is turned off and there is no server data
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	`+// spa shell should still prererender when +page.server.js exists but it has no load function`