Export vitePreprocess API (#509)

* feat: export vite preprocessors * feat: export vitePreprocess * chore: fix types * chore: simplify test * chore: improve type export * chore: add changeset * refactor: preprocess api * docs: add docs * chore: fix typo * chore: update docs * chore: make preprocess vite test esm * chore: default resolve config command by env * feat: use vite resolvedConfig when in vite * chore: update docs Co-authored-by: Ben McCann <[email protected]> * chore: log warning for useVitePreprocess option * docs: update comparison * chore: remove subpath export * chore: fix build * fix: typo Co-authored-by: Dominik G. <[email protected]> * chore: update docs Co-authored-by: Ben McCann <[email protected]> Co-authored-by: Ben McCann <[email protected]> Co-authored-by: Dominik G. <[email protected]>
sveltejs · Dec 2, 2022 · 0971449 · 0971449
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diff --git a/.changeset/wet-socks-ring.md b/.changeset/wet-socks-ring.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/vite-plugin-svelte': minor
+---
+
+Export `vitePreprocess()` Svelte preprocessor
diff --git a/docs/preprocess.md b/docs/preprocess.md
@@ -0,0 +1,34 @@
+# Preprocess
+
+`vite-plugin-svelte` also exports Vite preprocessors to preprocess Svelte components using Vite's built-in transformers.
+
+Compared to [`svelte-preprocess`](https://github.com/sveltejs/svelte-preprocess), Vite preprocessors share the same CSS configuration from the Vite config so you don't have to configure them twice. [`esbuild`](http://esbuild.github.io) is also used to transform TypeScript by default.
+
+However, `svelte-preprocess` does provide extra functionalities not available with Vite preprocessors, such as [template tag](https://github.com/sveltejs/svelte-preprocess#template-tag), [external files](https://github.com/sveltejs/svelte-preprocess#external-files), and [global styles](https://github.com/sveltejs/svelte-preprocess#global-style) ([though it's recommended to use import instead](./faq.md#where-should-i-put-my-global-styles)). If those features are required, you can still use `svelte-preprocess`, but make sure to turn off it's script and style preprocessing options.
+
+## vitePreprocess
+
+- **Type:** `{ script?: boolean, style?: boolean | InlineConfig | ResolvedConfig }`
+- **Default:** `{ script: true, style: true }`
+
+  A Svelte preprocessor that supports transforming TypeScript, PostCSS, SCSS, Less, Stylus, and SugarSS. These are transformed when the script or style tags have the respective `lang` attribute.
+
+  - TypeScript: `<script lang="ts">`
+  - PostCSS: `<style lang="postcss">`
+  - SCSS: `<style lang="scss">`
+  - Less: `<style lang="less">`
+  - Stylus: `<style lang="stylus">`
+  - SugarSS: `<style lang="sss">`
+
+  If required, you can turn script or style transforming off by setting the `script` or `style` option to `false`. The `style` option also accepts Vite's `InlineConfig` and `ResolvedConfig` types for advanced usage.
+
+  **Example:**
+
+  ```js
+  // svelte.config.js
+  import { vitePreprocess } from '@sveltejs/vite-plugin-svelte';
+
+  export default {
+    preprocess: [vitePreprocess()]
+  };
+  ```
diff --git a/packages/e2e-tests/preprocess-with-vite/package.json b/packages/e2e-tests/preprocess-with-vite/package.json
@@ -14,5 +14,5 @@
     "svelte": "^3.53.1",
     "vite": "^3.2.4"
   },
-  "type": "commonjs"
+  "type": "module"
 }
diff --git a/packages/e2e-tests/preprocess-with-vite/svelte.config.js b/packages/e2e-tests/preprocess-with-vite/svelte.config.js
@@ -0,0 +1,5 @@
+import { vitePreprocess } from '@sveltejs/vite-plugin-svelte';
+
+export default {
+	preprocess: [vitePreprocess()]
+};
diff --git a/packages/e2e-tests/preprocess-with-vite/vite.config.js b/packages/e2e-tests/preprocess-with-vite/vite.config.js
@@ -1,16 +1,10 @@
-const { svelte } = require('@sveltejs/vite-plugin-svelte');
-const { defineConfig } = require('vite');
+import { svelte } from '@sveltejs/vite-plugin-svelte';
+import { defineConfig } from 'vite';
 
-module.exports = defineConfig(({ command, mode }) => {
+export default defineConfig(({ command, mode }) => {
 	const isProduction = mode === 'production';
 	return {
-		plugins: [
-			svelte({
-				experimental: {
-					useVitePreprocess: true
-				}
-			})
-		],
+		plugins: [svelte()],
 		build: {
 			minify: isProduction
 		}

diff --git a/packages/vite-plugin-svelte/package.json b/packages/vite-plugin-svelte/package.json
@@ -6,9 +6,7 @@
   "files": [
     "dist",
     "src",
-    "README.md",
-    "LICENSE",
-    "package.json"
+    "*.d.ts"
   ],
   "type": "module",
   "main": "dist/index.cjs",
@@ -25,7 +23,7 @@
   },
   "scripts": {
     "dev": "pnpm build:ci --sourcemap --watch src",
-    "build:ci": "rimraf dist && tsup-node src/index.ts --format esm,cjs --no-splitting --shims",
+    "build:ci": "rimraf dist && tsup-node src/index.ts src/preprocess.ts --format esm,cjs --no-splitting --shims",
     "build": "pnpm build:ci --dts --sourcemap"
   },
   "engines": {

diff --git a/packages/vite-plugin-svelte/src/index.ts b/packages/vite-plugin-svelte/src/index.ts
@@ -238,6 +238,7 @@ export function svelte(inlineOptions?: Partial<Options>): Plugin[] {
 	return plugins.filter(Boolean);
 }
 
+export { vitePreprocess } from './preprocess';
 export { loadSvelteConfig } from './utils/load-svelte-config';
 
 export {

diff --git a/packages/vite-plugin-svelte/src/preprocess.ts b/packages/vite-plugin-svelte/src/preprocess.ts
@@ -0,0 +1,114 @@
+import path from 'path';
+import * as vite from 'vite';
+import type { ESBuildOptions, ResolvedConfig } from 'vite';
+// eslint-disable-next-line node/no-missing-import
+import type { Preprocessor, PreprocessorGroup } from 'svelte/types/compiler/preprocess';
+
+const supportedStyleLangs = ['css', 'less', 'sass', 'scss', 'styl', 'stylus', 'postcss', 'sss'];
+const supportedScriptLangs = ['ts'];
+
+export function vitePreprocess(opts?: {
+	script?: boolean;
+	style?: boolean | vite.InlineConfig | vite.ResolvedConfig;
+}) {
+	const preprocessor: PreprocessorGroup = {};
+	if (opts?.script !== false) {
+		preprocessor.script = viteScript().script;
+	}
+	if (opts?.style !== false) {
+		const styleOpts = typeof opts?.style == 'object' ? opts?.style : undefined;
+		preprocessor.style = viteStyle(styleOpts).style;
+	}
+	return preprocessor;
+}
+
+function viteScript(): { script: Preprocessor } {
+	return {
+		async script({ attributes, content, filename = '' }) {
+			const lang = attributes.lang as string;
+			if (!supportedScriptLangs.includes(lang)) return;
+			const transformResult = await vite.transformWithEsbuild(content, filename, {
+				loader: lang as ESBuildOptions['loader'],
+				target: 'esnext',
+				tsconfigRaw: {
+					compilerOptions: {
+						// svelte typescript needs this flag to work with type imports
+						importsNotUsedAsValues: 'preserve',
+						preserveValueImports: true
+					}
+				}
+			});
+			return {
+				code: transformResult.code,
+				map: transformResult.map
+			};
+		}
+	};
+}
+
+function viteStyle(config: vite.InlineConfig | vite.ResolvedConfig = {}): {
+	style: Preprocessor;
+} {
+	let transform: CssTransform;
+	const style: Preprocessor = async ({ attributes, content, filename = '' }) => {
+		const lang = attributes.lang as string;
+		if (!supportedStyleLangs.includes(lang)) return;
+		if (!transform) {
+			let resolvedConfig: vite.ResolvedConfig;
+			// @ts-expect-error special prop added if running in v-p-s
+			if (style.__resolvedConfig) {
+				// @ts-expect-error
+				resolvedConfig = style.__resolvedConfig;
+			} else if (isResolvedConfig(config)) {
+				resolvedConfig = config;
+			} else {
+				resolvedConfig = await vite.resolveConfig(
+					config,
+					process.env.NODE_ENV === 'production' ? 'build' : 'serve'
+				);
+			}
+			transform = getCssTransformFn(resolvedConfig);
+		}
+		const moduleId = `${filename}.${lang}`;
+		const result = await transform(content, moduleId);
+		// patch sourcemap source to point back to original filename
+		if (result.map?.sources?.[0] === moduleId) {
+			result.map.sources[0] = path.basename(filename);
+		}
+		return {
+			code: result.code,
+			map: result.map ?? undefined
+		};
+	};
+	// @ts-expect-error tag so can be found by v-p-s
+	style.__resolvedConfig = null;
+	return { style };
+}
+
+// eslint-disable-next-line no-unused-vars
+type CssTransform = (code: string, filename: string) => Promise<{ code: string; map?: any }>;
+
+function getCssTransformFn(config: ResolvedConfig): CssTransform {
+	// API is only available in Vite 3.2 and above
+	// TODO: Remove Vite plugin hack when bump peer dep to Vite 3.2
+	if (vite.preprocessCSS) {
+		return async (code, filename) => {
+			return vite.preprocessCSS(code, filename, config);
+		};
+	} else {
+		const pluginName = 'vite:css';
+		const plugin = config.plugins.find((p) => p.name === pluginName);
+		if (!plugin) {
+			throw new Error(`failed to find plugin ${pluginName}`);
+		}
+		if (!plugin.transform) {
+			throw new Error(`plugin ${pluginName} has no transform`);
+		}
+		// @ts-expect-error
+		return plugin.transform.bind(null);
+	}
+}
+
+function isResolvedConfig(config: any): config is vite.ResolvedConfig {
+	return !!config.inlineConfig;
+}
diff --git a/packages/vite-plugin-svelte/src/utils/options.ts b/packages/vite-plugin-svelte/src/utils/options.ts
@@ -532,6 +532,15 @@ function buildExtraConfigForSvelte(config: UserConfig) {
 }
 
 export function patchResolvedViteConfig(viteConfig: ResolvedConfig, options: ResolvedOptions) {
+	if (options.preprocess) {
+		for (const preprocessor of arraify(options.preprocess)) {
+			if (preprocessor.style && '__resolvedConfig' in preprocessor.style) {
+				preprocessor.style.__resolvedConfig = viteConfig;
+			}
+		}
+	}
+
+	// replace facade esbuild plugin with a real one
 	const facadeEsbuildSveltePlugin = viteConfig.optimizeDeps.esbuildOptions?.plugins?.find(
 		(plugin) => plugin.name === facadeEsbuildSveltePluginName
 	);
@@ -540,6 +549,10 @@ export function patchResolvedViteConfig(viteConfig: ResolvedConfig, options: Res
 	}
 }
 
+function arraify<T>(value: T | T[]): T[] {
+	return Array.isArray(value) ? value : [value];
+}
+
 export type Options = Omit<SvelteOptions, 'vitePlugin'> & PluginOptionsInline;
 
 interface PluginOptionsInline extends PluginOptions {

diff --git a/packages/vite-plugin-svelte/src/utils/preprocess.ts b/packages/vite-plugin-svelte/src/utils/preprocess.ts
@@ -1,93 +1,18 @@
-import * as vite from 'vite';
-import type { ESBuildOptions, ResolvedConfig, Plugin } from 'vite';
+import type { ResolvedConfig, Plugin } from 'vite';
 import MagicString from 'magic-string';
 import { preprocess } from 'svelte/compiler';
-import { Preprocessor, PreprocessorGroup, Processed, ResolvedOptions } from './options';
+import { PreprocessorGroup, Processed, ResolvedOptions } from './options';
 import { log } from './log';
 import { buildSourceMap } from './sourcemap';
 import path from 'path';
-
-const supportedStyleLangs = ['css', 'less', 'sass', 'scss', 'styl', 'stylus', 'postcss'];
-
-const supportedScriptLangs = ['ts'];
-
-function createViteScriptPreprocessor(): Preprocessor {
-	return async ({ attributes, content, filename = '' }) => {
-		const lang = attributes.lang as string;
-		if (!supportedScriptLangs.includes(lang)) return;
-		const transformResult = await vite.transformWithEsbuild(content, filename, {
-			loader: lang as ESBuildOptions['loader'],
-			target: 'esnext',
-			tsconfigRaw: {
-				compilerOptions: {
-					// svelte typescript needs this flag to work with type imports
-					importsNotUsedAsValues: 'preserve',
-					preserveValueImports: true
-				}
-			}
-		});
-		return {
-			code: transformResult.code,
-			map: transformResult.map
-		};
-	};
-}
-
-function createViteStylePreprocessor(config: ResolvedConfig): Preprocessor {
-	const transform = getCssTransformFn(config);
-	return async ({ attributes, content, filename = '' }) => {
-		const lang = attributes.lang as string;
-		if (!supportedStyleLangs.includes(lang)) return;
-		const moduleId = `${filename}.${lang}`;
-		const result = await transform(content, moduleId);
-		// patch sourcemap source to point back to original filename
-		if (result.map?.sources?.[0] === moduleId) {
-			result.map.sources[0] = path.basename(filename);
-		}
-		return {
-			code: result.code,
-			map: result.map ?? undefined
-		};
-	};
-}
-
-// eslint-disable-next-line no-unused-vars
-type CssTransform = (code: string, filename: string) => Promise<{ code: string; map?: any }>;
-
-function getCssTransformFn(config: ResolvedConfig): CssTransform {
-	// API is only available in Vite 3.2 and above
-	// TODO: Remove Vite plugin hack when bump peer dep to Vite 3.2
-	if (vite.preprocessCSS) {
-		return async (code, filename) => {
-			return vite.preprocessCSS(code, filename, config);
-		};
-	} else {
-		const pluginName = 'vite:css';
-		const plugin = config.plugins.find((p) => p.name === pluginName);
-		if (!plugin) {
-			throw new Error(`failed to find plugin ${pluginName}`);
-		}
-		if (!plugin.transform) {
-			throw new Error(`plugin ${pluginName} has no transform`);
-		}
-		// @ts-expect-error
-		return plugin.transform.bind(null);
-	}
-}
+import { vitePreprocess } from '../preprocess';
 
 function createVitePreprocessorGroup(config: ResolvedConfig): PreprocessorGroup {
 	return {
 		markup({ content, filename }) {
-			return preprocess(
-				content,
-				{
-					script: createViteScriptPreprocessor(),
-					style: createViteStylePreprocessor(config)
-				},
-				{ filename }
-			);
+			return preprocess(content, vitePreprocess({ style: config }), { filename });
 		}
-	} as PreprocessorGroup;
+	};
 }
 
 /**
@@ -117,7 +42,9 @@ function buildExtraPreprocessors(options: ResolvedOptions, config: ResolvedConfi
 	const appendPreprocessors: PreprocessorGroup[] = [];
 
 	if (options.experimental?.useVitePreprocess) {
-		log.debug('adding vite preprocessor');
+		log.warn(
+			'`experimental.useVitePreprocess` is deprecated. Use the `vitePreprocess()` preprocessor instead. See https://github.com/sveltejs/vite-plugin-svelte/blob/main/docs/preprocess.md for more information.'
+		);
 		prependPreprocessors.push(createVitePreprocessorGroup(config));
 	}