feat: add `bundleStrategy: 'inline' (#13193)

* feat: add `codeSplitJs` option

* fix: only use `manualChunks` when `!codeSplitJS`

* Create beige-carpets-wave.md

* chore: regenerate types

* chore: add option to `options` app for tests

* chore: move tests from `options` to `options-2` and add test for bundle

* chore: rename chunk, add css test

* chore: rename option to `codeSplit`

* chore: apply suggestions from code review

* this looks unintentional, reverting

* tweak docs

* DRY out

* get rid of Promise.all when codeSplit: false

* types

* rename to bundleStrategy

* more detail

* pretty sure this is unused

* tweak

* small tweaks

* inline strategy

* omit modulepreloads when inlining script

* regenerate

* fix

* changeset

* regenerate

* fix

* jsdoc

* allow trailing /index.html when serving from filesystem

* treat current directory as base when using hash-based routing

* make self-contained apps possible

* lint

* oops

---------

Co-authored-by: paoloricciuti <ricciutipaolo@gmail.com>
Co-authored-by: Simon Holthausen <simon.holthausen@vercel.com>

.changeset/strange-geese-train.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': minor
+---
+
+feat: add `bundleStrategy: 'inline'` option

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

@@ -143,7 +143,7 @@ const options = object(
 
 			output: object({
 				preloadStrategy: list(['modulepreload', 'preload-js', 'preload-mjs']),
-				bundleStrategy: list(['split', 'single'])
+				bundleStrategy: list(['split', 'single', 'inline'])
 			}),
 
 			paths: object({

packages/kit/src/exports/public.d.ts

@@ -499,14 +499,15 @@ export interface KitConfig {
 		 */
 		preloadStrategy?: 'modulepreload' | 'preload-js' | 'preload-mjs';
 		/**
-		 * If `'split'`, splits the app up into multiple .js/.css files so that they are loaded lazily as the user navigates around the app. This is the default, and is recommended for most scenarios.
-		 * If `'single'`, creates just one .js bundle and one .css file containing code for the entire app.
+		 * - If `'split'`, splits the app up into multiple .js/.css files so that they are loaded lazily as the user navigates around the app. This is the default, and is recommended for most scenarios.
+		 * - If `'single'`, creates just one .js bundle and one .css file containing code for the entire app.
+		 * - If `'inline'`, inlines all JavaScript and CSS of the entire app into the HTML. The result is usable without a server (i.e. you can just open the file in your browser).
 		 *
 		 * When using `'split'`, you can also adjust the bundling behaviour by setting [`output.experimentalMinChunkSize`](https://rollupjs.org/configuration-options/#output-experimentalminchunksize) and [`output.manualChunks`](https://rollupjs.org/configuration-options/#output-manualchunks)inside your Vite config's [`build.rollupOptions`](https://vite.dev/config/build-options.html#build-rollupoptions).
 		 * @default 'split'
 		 * @since 2.13.0
 		 */
-		bundleStrategy?: 'split' | 'single';
+		bundleStrategy?: 'split' | 'single' | 'inline';
 	};
 	paths?: {
 		/**

packages/kit/src/exports/vite/index.js

@@ -631,26 +631,30 @@ async function kit({ svelte_config }) {
 				const client_base =
 					kit.paths.relative !== false || kit.paths.assets ? './' : kit.paths.base || '/';
 
+				const inline = !ssr && svelte_config.kit.output.bundleStrategy === 'inline';
+				const split = ssr || svelte_config.kit.output.bundleStrategy === 'split';
+
 				new_config = {
 					base: ssr ? assets_base(kit) : client_base,
 					build: {
 						copyPublicDir: !ssr,
-						cssCodeSplit: true,
+						cssCodeSplit: svelte_config.kit.output.bundleStrategy !== 'inline',
 						cssMinify: initial_config.build?.minify == null ? true : !!initial_config.build.minify,
 						// don't use the default name to avoid collisions with 'static/manifest.json'
 						manifest: '.vite/manifest.json', // TODO: remove this after bumping peer dep to vite 5
 						outDir: `${out}/${ssr ? 'server' : 'client'}`,
 						rollupOptions: {
-							input,
+							input: inline ? input['bundle'] : input,
 							output: {
-								format: 'esm',
+								format: inline ? 'iife' : 'esm',
+								name: `__sveltekit_${version_hash}.app`,
 								entryFileNames: ssr ? '[name].js' : `${prefix}/[name].[hash].${ext}`,
 								chunkFileNames: ssr ? 'chunks/[name].js' : `${prefix}/chunks/[name].[hash].${ext}`,
 								assetFileNames: `${prefix}/assets/[name].[hash][extname]`,
 								hoistTransitiveImports: false,
 								sourcemapIgnoreList,
-								manualChunks:
-									svelte_config.kit.output.bundleStrategy === 'single' ? () => 'bundle' : undefined
+								manualChunks: split ? undefined : () => 'bundle',
+								inlineDynamicImports: false
 							},
 							preserveEntrySignatures: 'strict'
 						},
@@ -868,6 +872,22 @@ async function kit({ svelte_config }) {
 							(chunk) => chunk.type === 'chunk' && chunk.modules[env_dynamic_public]
 						)
 					};
+
+					if (svelte_config.kit.output.bundleStrategy === 'inline') {
+						const style = /** @type {import('rollup').OutputAsset} */ (
+							output.find(
+								(chunk) =>
+									chunk.type === 'asset' &&
+									chunk.names.length === 1 &&
+									chunk.names[0] === 'style.css'
+							)
+						);
+
+						build_data.client.inline = {
+							script: read(`${out}/client/${start.file}`),
+							style: /** @type {string | undefined} */ (style?.source)
+						};
+					}
 				}
 
 				const css = output.filter(

packages/kit/src/runtime/client/bundle.js

@@ -1,4 +1,4 @@
-/* if `bundleStrategy === 'single'`, this file is used as the entry point */
+/* if `bundleStrategy` is 'single' or 'inline', this file is used as the entry point */
 
 import * as kit from './entry.js';
 

packages/kit/src/runtime/client/utils.js

@@ -303,12 +303,25 @@ export function create_updated_store() {
  * - uses hash router and pathname is more than base
  * @param {URL} url
  * @param {string} base
- * @param {boolean} has_pathname_in_hash
+ * @param {boolean} hash_routing
  */
-export function is_external_url(url, base, has_pathname_in_hash) {
-	return (
-		url.origin !== origin ||
-		!url.pathname.startsWith(base) ||
-		(has_pathname_in_hash && url.pathname !== (base || '/'))
-	);
+export function is_external_url(url, base, hash_routing) {
+	if (url.origin !== origin || !url.pathname.startsWith(base)) {
+		return true;
+	}
+
+	if (hash_routing) {
+		if (url.pathname === base + '/') {
+			return false;
+		}
+
+		// be lenient if serving from filesystem
+		if (url.protocol === 'file:' && url.pathname.replace(/\/[^/]+\.html?$/, '') === base) {
+			return false;
+		}
+
+		return true;
+	}
+
+	return false;
 }

packages/kit/src/runtime/server/page/render.js

@@ -95,16 +95,21 @@ export async function render_response({
 	let base_expression = s(paths.base);
 
 	// if appropriate, use relative paths for greater portability
-	if (paths.relative && !state.prerendering?.fallback) {
-		const segments = event.url.pathname.slice(paths.base.length).split('/').slice(2);
+	if (paths.relative) {
+		if (!state.prerendering?.fallback) {
+			const segments = event.url.pathname.slice(paths.base.length).split('/').slice(2);
 
-		base = segments.map(() => '..').join('/') || '.';
+			base = segments.map(() => '..').join('/') || '.';
 
-		// resolve e.g. '../..' against current location, then remove trailing slash
-		base_expression = `new URL(${s(base)}, location).pathname.slice(0, -1)`;
+			// resolve e.g. '../..' against current location, then remove trailing slash
+			base_expression = `new URL(${s(base)}, location).pathname.slice(0, -1)`;
 
-		if (!paths.assets || (paths.assets[0] === '/' && paths.assets !== SVELTE_KIT_ASSETS)) {
-			assets = base;
+			if (!paths.assets || (paths.assets[0] === '/' && paths.assets !== SVELTE_KIT_ASSETS)) {
+				assets = base;
+			}
+		} else if (options.hash_routing) {
+			// we have to assume that we're in the right place
+			base_expression = "new URL('.', location).pathname.slice(0, -1)";
 		}
 	}
 
@@ -197,7 +202,7 @@ export async function render_response({
 			for (const url of node.stylesheets) stylesheets.add(url);
 			for (const url of node.fonts) fonts.add(url);
 
-			if (node.inline_styles) {
+			if (node.inline_styles && !client.inline) {
 				Object.entries(await node.inline_styles()).forEach(([k, v]) => inline_styles.set(k, v));
 			}
 		}
@@ -223,6 +228,10 @@ export async function render_response({
 		return `${assets}/${path}`;
 	};
 
+	if (client.inline?.style) {
+		head += `\n\t<style>${client.inline.style}</style>`;
+	}
+
 	if (inline_styles.size > 0) {
 		const content = Array.from(inline_styles.values()).join('\n');
 
@@ -293,17 +302,19 @@ export async function render_response({
 			modulepreloads.add(`${options.app_dir}/env.js`);
 		}
 
-		const included_modulepreloads = Array.from(modulepreloads, (dep) => prefixed(dep)).filter(
-			(path) => resolve_opts.preload({ type: 'js', path })
-		);
-
-		for (const path of included_modulepreloads) {
-			// see the kit.output.preloadStrategy option for details on why we have multiple options here
-			link_header_preloads.add(`<${encodeURI(path)}>; rel="modulepreload"; nopush`);
-			if (options.preload_strategy !== 'modulepreload') {
-				head += `\n\t\t<link rel="preload" as="script" crossorigin="anonymous" href="${path}">`;
-			} else if (state.prerendering) {
-				head += `\n\t\t<link rel="modulepreload" href="${path}">`;
+		if (!client.inline) {
+			const included_modulepreloads = Array.from(modulepreloads, (dep) => prefixed(dep)).filter(
+				(path) => resolve_opts.preload({ type: 'js', path })
+			);
+
+			for (const path of included_modulepreloads) {
+				// see the kit.output.preloadStrategy option for details on why we have multiple options here
+				link_header_preloads.add(`<${encodeURI(path)}>; rel="modulepreload"; nopush`);
+				if (options.preload_strategy !== 'modulepreload') {
+					head += `\n\t\t<link rel="preload" as="script" crossorigin="anonymous" href="${path}">`;
+				} else if (state.prerendering) {
+					head += `\n\t\t<link rel="modulepreload" href="${path}">`;
+				}
 			}
 		}
 
@@ -392,15 +403,19 @@ export async function render_response({
 			args.push(`{\n${indent}\t${hydrate.join(`,\n${indent}\t`)}\n${indent}}`);
 		}
 
-		// `client.app` is a proxy for `bundleStrategy !== 'single'`
-		const boot = client.app
-			? `Promise.all([
+		// `client.app` is a proxy for `bundleStrategy === 'split'`
+		const boot = client.inline
+			? `${client.inline.script}
+
+					__sveltekit_${options.version_hash}.app.start(${args.join(', ')});`
+			: client.app
+				? `Promise.all([
 						import(${s(prefixed(client.start))}),
 						import(${s(prefixed(client.app))})
 					]).then(([kit, app]) => {
 						kit.start(app, ${args.join(', ')});
 					});`
-			: `import(${s(prefixed(client.start))}).then((app) => {
+				: `import(${s(prefixed(client.start))}).then((app) => {
 						app.start(${args.join(', ')})
 					});`;
 

packages/kit/src/types/internal.d.ts

@@ -74,6 +74,10 @@ export interface BuildData {
 		stylesheets: string[];
 		fonts: string[];
 		uses_env_dynamic_public: boolean;
+		inline?: {
+			script: string;
+			style: string | undefined;
+		};
 	} | null;
 	server_manifest: import('vite').Manifest;
 }

packages/kit/types/index.d.ts

@@ -481,14 +481,15 @@ declare module '@sveltejs/kit' {
 			 */
 			preloadStrategy?: 'modulepreload' | 'preload-js' | 'preload-mjs';
 			/**
-			 * If `'split'`, splits the app up into multiple .js/.css files so that they are loaded lazily as the user navigates around the app. This is the default, and is recommended for most scenarios.
-			 * If `'single'`, creates just one .js bundle and one .css file containing code for the entire app.
+			 * - If `'split'`, splits the app up into multiple .js/.css files so that they are loaded lazily as the user navigates around the app. This is the default, and is recommended for most scenarios.
+			 * - If `'single'`, creates just one .js bundle and one .css file containing code for the entire app.
+			 * - If `'inline'`, inlines all JavaScript and CSS of the entire app into the HTML. The result is usable without a server (i.e. you can just open the file in your browser).
 			 *
 			 * When using `'split'`, you can also adjust the bundling behaviour by setting [`output.experimentalMinChunkSize`](https://rollupjs.org/configuration-options/#output-experimentalminchunksize) and [`output.manualChunks`](https://rollupjs.org/configuration-options/#output-manualchunks)inside your Vite config's [`build.rollupOptions`](https://vite.dev/config/build-options.html#build-rollupoptions).
 			 * @default 'split'
 			 * @since 2.13.0
 			 */
-			bundleStrategy?: 'split' | 'single';
+			bundleStrategy?: 'split' | 'single' | 'inline';
 		};
 		paths?: {
 			/**
@@ -1667,6 +1668,10 @@ declare module '@sveltejs/kit' {
 			stylesheets: string[];
 			fonts: string[];
 			uses_env_dynamic_public: boolean;
+			inline?: {
+				script: string;
+				style: string | undefined;
+			};
 		} | null;
 		server_manifest: import('vite').Manifest;
 	}