[feat] add prerender.subfolders setting (#2632)

* [feat] add prerender.subfolders setting

- Fixes #1443

Setting the kit.prerender.subfolders to false (default is true) will change the filename generation from "/about/index.html" to "/about.html"

* remove separate prerender tests in favour of the new test suite

* on second thoughts, save that for a follow-up PR

* remove unused file

* rename prerender.subfolders to prerender.createIndexFiles

Co-authored-by: Bob Fanger <b.fanger@wearetriple.com>
Co-authored-by: Rich Harris <hello@rich-harris.dev>

.changeset/modern-pillows-beam.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+add prerender.subfolders setting

documentation/docs/14-configuration.md

@@ -54,6 +54,7 @@ const config = {
 			concurrency: 1,
 			crawl: true,
 			enabled: true,
+			subfolders: true,
 			entries: ['*'],
 			onError: 'fail'
 		},
@@ -196,6 +197,7 @@ See [Prerendering](#page-options-prerender). An object containing zero or more o
 - `crawl` — determines whether SvelteKit should find pages to prerender by following links from the seed page(s)
 - `enabled` — set to `false` to disable prerendering altogether
 - `entries` — an array of pages to prerender, or start crawling from (if `crawl: true`). The `*` string includes all non-dynamic routes (i.e. pages with no `[parameters]` )
+- `subfolders` - set to `false` to disable subfolders for routes: instead of `about/index.html` render `about.html`
 - `onError`
 
   - `'fail'` — (default) fails the build when a routing error is encountered when following a link

packages/kit/src/core/adapt/prerender/prerender.js

@@ -111,6 +111,25 @@ export async function prerender({ cwd, out, log, config, build_data, fallback, a
 
 	const q = queue(config.kit.prerender.concurrency);
 
+	/**
+	 * @param {string} path
+	 * @param {boolean} is_html
+	 */
+	function output_filename(path, is_html) {
+		if (path === '/') {
+			return '/index.html';
+		}
+		const parts = path.split('/');
+		if (is_html && parts[parts.length - 1] !== 'index.html') {
+			if (config.kit.prerender.createIndexFiles) {
+				parts.push('index.html');
+			} else {
+				parts[parts.length - 1] += '.html';
+			}
+		}
+		return parts.join('/');
+	}
+
 	/**
 	 * @param {string} decoded_path
 	 * @param {string?} referrer
@@ -149,12 +168,7 @@ export async function prerender({ cwd, out, log, config, build_data, fallback, a
 			const type = rendered.headers.get('content-type');
 			const is_html = response_type === REDIRECT || type === 'text/html';
 
-			const parts = decoded_path.split('/');
-			if (is_html && parts[parts.length - 1] !== 'index.html') {
-				parts.push('index.html');
-			}
-
-			const file = `${out}${parts.join('/')}`;
+			const file = `${out}${output_filename(decoded_path, is_html)}`;
 
 			if (response_type === REDIRECT) {
 				const location = rendered.headers.get('location');
@@ -199,12 +213,7 @@ export async function prerender({ cwd, out, log, config, build_data, fallback, a
 
 				const is_html = headers.get('content-type') === 'text/html';
 
-				const parts = dependency_path.split('/');
-				if (is_html && parts[parts.length - 1] !== 'index.html') {
-					parts.push('index.html');
-				}
-
-				const file = `${out}${parts.join('/')}`;
+				const file = `${out}${output_filename(dependency_path, is_html)}`;
 				mkdirp(dirname(file));
 
 				writeFileSync(

packages/kit/src/core/adapt/test/index.js

@@ -99,6 +99,7 @@ suite('prerender', async () => {
 			appDir: '_app',
 			prerender: {
 				concurrency: 1,
+				createIndexFiles: true,
 				enabled: true,
 				entries: ['*']
 			}

packages/kit/src/core/config/index.spec.js

@@ -85,6 +85,7 @@ const get_defaults = (prefix = '') => ({
 		prerender: {
 			concurrency: 1,
 			crawl: true,
+			createIndexFiles: true,
 			enabled: true,
 			entries: ['*'],
 			force: undefined,

packages/kit/src/core/config/options.js

@@ -186,6 +186,7 @@ const options = object(
 			prerender: object({
 				concurrency: number(1),
 				crawl: boolean(true),
+				createIndexFiles: boolean(true),
 				enabled: boolean(true),
 				entries: validate(['*'], (input, keypath) => {
 					if (!Array.isArray(input) || !input.every((page) => typeof page === 'string')) {

packages/kit/test/prerendering/options/svelte.config.js

@@ -17,6 +17,10 @@ const config = {
 			assets: 'https://cdn.example.com/stuff'
 		},
 
+		prerender: {
+			createIndexFiles: false
+		},
+
 		vite: {
 			build: {
 				minify: false

packages/kit/test/prerendering/options/test/test.js

@@ -15,7 +15,7 @@ test('prerenders /path-base', () => {
 });
 
 test('prerenders nested /path-base', () => {
-	const content = read('/nested/index.html');
+	const content = read('/nested.html');
 	assert.ok(content.includes('<h1>nested hello</h1>'));
 	assert.ok(content.includes('http://sveltekit-prerender/path-base/nested'));
 });

packages/kit/types/config.d.ts

@@ -153,6 +153,7 @@ export interface Config {
 		prerender?: {
 			concurrency?: number;
 			crawl?: boolean;
+			createIndexFiles?: boolean;
 			enabled?: boolean;
 			entries?: string[];
 			onError?: PrerenderOnErrorValue;