sveltejs · Rich-Harris · Apr 13, 2022 · Apr 13, 2022 · Apr 13, 2022 · Apr 13, 2022
diff --git a/.changeset/red-adults-wonder.md b/.changeset/red-adults-wonder.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+Only render fallback when prerendering is enabled
diff --git a/packages/adapter-static/README.md b/packages/adapter-static/README.md
@@ -71,6 +71,8 @@ export default {
 
 When operating in SPA mode, you can omit `config.kit.prerender.default` (or set it to `false`, its default value), and only pages that have the [`prerender`](https://kit.svelte.dev/docs/page-options#prerender) option set will be prerendered at build time.
 
+SvelteKit will still crawl your app's entry points looking for prerenderable pages. If `svelte-kit build` fails because of pages that can't be loaded outside the browser, you can set `config.kit.prerender.entries` to `[]` to prevent this from happening. (Setting `config.kit.prerender.enabled` also has this effect, but would prevent the fallback page from being generated.)
+
 > ⚠️ During development, SvelteKit will still attempt to server-side render your routes. This means accessing things that are only available in the browser (such as the `window` object) will result in errors, even though this would be valid in the output app. To align the behavior of SvelteKit's dev mode with your SPA, you can [call `resolve()` with a parameter of `{ssr: false}` inside the `handle()` hook](https://kit.svelte.dev/docs/hooks#handle).
 
 ## GitHub Pages

diff --git a/packages/kit/src/core/build/prerender/prerender.js b/packages/kit/src/core/build/prerender/prerender.js
@@ -55,6 +55,10 @@ export async function prerender({ config, entries, files, log }) {
 		paths: []
 	};
 
+	if (!config.kit.prerender.enabled) {
+		return prerendered;
+	}
+
 	installFetch();
 
 	const server_root = join(config.kit.outDir, 'output');
@@ -71,23 +75,6 @@ export async function prerender({ config, entries, files, log }) {
 
 	const server = new Server(manifest);
 
-	const rendered = await server.respond(new Request('http://sveltekit-prerender/[fallback]'), {
-		getClientAddress,
-		prerender: {
-			fallback: true,
-			default: false,
-			dependencies: new Map()
-		}
-	});
-
-	const file = `${config.kit.outDir}/output/prerendered/fallback.html`;
-	mkdirp(dirname(file));
-	writeFileSync(file, await rendered.text());
-
-	if (!config.kit.prerender.enabled) {
-		return prerendered;
-	}
-
 	const error = normalise_error_handler(log, config.kit.prerender.onError);
 
 	const q = queue(config.kit.prerender.concurrency);
@@ -281,6 +268,19 @@ export async function prerender({ config, entries, files, log }) {
 		await q.done();
 	}
 
+	const rendered = await server.respond(new Request('http://sveltekit-prerender/[fallback]'), {
+		getClientAddress,
+		prerender: {
+			fallback: true,
+			default: false,
+			dependencies: new Map()
+		}
+	});
+
+	const file = `${config.kit.outDir}/output/prerendered/fallback.html`;
+	mkdirp(dirname(file));
+	writeFileSync(file, await rendered.text());
+
 	return prerendered;
 }
 

diff --git a/packages/kit/test/prerendering/disabled/package.json b/packages/kit/test/prerendering/disabled/package.json
@@ -0,0 +1,20 @@
+{
+	"name": "prerendering-test-basics",
+	"private": true,
+	"version": "0.0.2-next.0",
+	"scripts": {
+		"dev": "node ../../cli.js dev",
+		"build": "node ../../cli.js build",
+		"preview": "node ../../cli.js preview",
+		"check": "tsc && svelte-check",
+		"test": "npm run build"
+	},
+	"devDependencies": {
+		"@sveltejs/kit": "workspace:*",
+		"svelte": "^3.43.0",
+		"svelte-check": "^2.5.0",
+		"typescript": "~4.6.2",
+		"uvu": "^0.5.2"
+	},
+	"type": "module"
+}
diff --git a/packages/kit/test/prerendering/disabled/src/app.html b/packages/kit/test/prerendering/disabled/src/app.html
@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html lang="en">
+	<head>
+		<meta charset="utf-8" />
+		<meta name="viewport" content="width=device-width, initial-scale=1" />
+		%svelte.head%
+	</head>
+	<body>
+		%svelte.body%
+	</body>
+</html>
diff --git a/packages/kit/test/prerendering/disabled/src/hooks.js b/packages/kit/test/prerendering/disabled/src/hooks.js
@@ -0,0 +1 @@
+throw new Error('this file should not be loaded if prerendering is disabled');
diff --git a/packages/kit/test/prerendering/disabled/src/routes/index.svelte b/packages/kit/test/prerendering/disabled/src/routes/index.svelte
@@ -0,0 +1 @@
+<h1>not prerendered</h1>
diff --git a/packages/kit/test/prerendering/disabled/svelte.config.js b/packages/kit/test/prerendering/disabled/svelte.config.js
@@ -0,0 +1,27 @@
+import path from 'path';
+import adapter from '../../../../adapter-static/index.js';
+
+/** @type {import('@sveltejs/kit').Config} */
+const config = {
+	kit: {
+		adapter: adapter(),
+
+		prerender: {
+			enabled: false
+		},
+
+		vite: {
+			build: {
+				minify: false
+			},
+			clearScreen: false,
+			server: {
+				fs: {
+					allow: [path.resolve('../../../src')]
+				}
+			}
+		}
+	}
+};
+
+export default config;
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml