Svelte: Fix docs generating when using lang="ts" or optional chaining

code/e2e-tests/framework-svelte.spec.ts

@@ -0,0 +1,40 @@
+/* eslint-disable jest/no-disabled-tests */
+import { test, expect } from '@playwright/test';
+import process from 'process';
+import { SbPage } from './util';
+
+const storybookUrl = process.env.STORYBOOK_URL || 'http://localhost:6006';
+const templateName = process.env.STORYBOOK_TEMPLATE_NAME;
+
+test.describe('Svelte', () => {
+  test.skip(
+    // eslint-disable-next-line jest/valid-title
+    !templateName?.includes('svelte'),
+    'Only run this test on Svelte'
+  );
+
+  test.beforeEach(async ({ page }) => {
+    await page.goto(storybookUrl);
+    await new SbPage(page).waitUntilLoaded();
+  });
+
+  test('JS story has auto-generated args table', async ({ page }) => {
+    const sbPage = new SbPage(page);
+
+    await sbPage.navigateToStory('stories/renderers/svelte/js-docs', 'docs');
+    const root = sbPage.previewRoot();
+    const argsTable = root.locator('.docblock-argstable');
+    await expect(argsTable).toContainText('Rounds the button');
+  });
+
+  test('TS story has auto-generated args table', async ({ page }) => {
+    // eslint-disable-next-line jest/valid-title
+    test.skip(!templateName?.endsWith('ts') || false, 'Only test TS story in TS templates');
+    const sbPage = new SbPage(page);
+
+    await sbPage.navigateToStory('stories/renderers/svelte/ts-docs', 'docs');
+    const root = sbPage.previewRoot();
+    const argsTable = root.locator('.docblock-argstable');
+    await expect(argsTable).toContainText('Rounds the button');
+  });
+});

code/frameworks/svelte-vite/package.json

@@ -52,6 +52,7 @@
     "@storybook/svelte": "workspace:*",
     "@sveltejs/vite-plugin-svelte": "^2.4.2",
     "magic-string": "^0.30.0",
+    "svelte-preprocess": "^5.0.4",
     "sveltedoc-parser": "^4.2.1",
     "ts-dedent": "^2.2.0"
   },

code/frameworks/svelte-vite/src/plugins/svelte-docgen.ts

@@ -7,6 +7,23 @@ import type { SvelteParserOptions } from 'sveltedoc-parser';
 import { logger } from '@storybook/node-logger';
 import { preprocess } from 'svelte/compiler';
 import { createFilter } from 'vite';
+import { replace, typescript } from 'svelte-preprocess';
+
+/*
+ * Patch sveltedoc-parser internal options.
+ * Waiting for a fix for https://github.com/alexprey/sveltedoc-parser/issues/87
+ */
+const svelteDocParserOptions = require('sveltedoc-parser/lib/options.js');
+
+svelteDocParserOptions.getAstDefaultOptions = () => ({
+  range: true,
+  loc: true,
+  comment: true,
+  tokens: true,
+  ecmaVersion: 12,
+  sourceType: 'module',
+  ecmaFeatures: {},
+});
 
 // Most of the code here should probably be exported by @storybook/svelte and reused here.
 // See: https://github.com/storybookjs/storybook/blob/next/app/svelte/src/server/svelte-docgen-loader.ts
@@ -48,19 +65,43 @@ export function svelteDocgen(svelteOptions: Record<string, any> = {}): PluginOpt
   const include = /\.(svelte)$/;
   const filter = createFilter(include);
 
+  let docPreprocessOptions: Parameters<typeof preprocess>[1] | undefined;
+
   return {
     name: 'storybook:svelte-docgen-plugin',
     async transform(src: string, id: string) {
       if (!filter(id)) return undefined;
 
+      if (preprocessOptions && !docPreprocessOptions) {
+        /*
+         * We can't use vitePreprocess() for the documentation
+         * because it uses esbuild which removes jsdoc.
+         *
+         * By default, only typescript is transpiled, and style tags are removed.
+         *
+         * Note: these preprocessors are only used to make the component
+         * compatible to sveltedoc-parser (no ts), not to compile
+         * the component.
+         */
+        docPreprocessOptions = [replace([[/<style.+<\/style>/gims, '']])];
+
+        try {
+          const ts = require.resolve('typescript');
+          if (ts) {
+            docPreprocessOptions.unshift(typescript());
+          }
+        } catch {
+          // this will error in JavaScript-only projects, this is okay
+        }
+      }
+
       const resource = path.relative(cwd, id);
 
       let docOptions;
-      if (preprocessOptions) {
-        // eslint-disable-next-line @typescript-eslint/no-shadow
-        const src = fs.readFileSync(resource).toString();
+      if (docPreprocessOptions) {
+        const rawSource = fs.readFileSync(resource).toString();
 
-        const { code: fileContent } = await preprocess(src, preprocessOptions, {
+        const { code: fileContent } = await preprocess(rawSource, docPreprocessOptions, {
           filename: resource,
         });
 
@@ -79,21 +120,24 @@ export function svelteDocgen(svelteOptions: Record<string, any> = {}): PluginOpt
 
       const s = new MagicString(src);
 
+      let componentDoc: any;
       try {
-        const componentDoc = await svelteDoc.parse(options);
-        // get filename for source content
-        const file = path.basename(resource);
-
-        componentDoc.name = path.basename(file);
-
-        const componentName = getNameFromFilename(resource);
-        s.append(`;${componentName}.__docgen = ${JSON.stringify(componentDoc)}`);
+        componentDoc = await svelteDoc.parse(options);
       } catch (error: any) {
+        componentDoc = { keywords: [], data: [] };
         if (logDocgen) {
           logger.error(error);
         }
       }
 
+      // get filename for source content
+      const file = path.basename(resource);
+
+      componentDoc.name = path.basename(file);
+
+      const componentName = getNameFromFilename(resource);
+      s.append(`;${componentName}.__docgen = ${JSON.stringify(componentDoc)}`);
+
       return {
         code: s.toString(),
         map: s.generateMap({ hires: true, source: id }),

code/frameworks/svelte-vite/template/stories_svelte-vite-default-ts/ButtonTypeScript.svelte

@@ -0,0 +1,38 @@
+<script lang="ts">
+  /**
+   * @component Button TypeScript
+   * @wrapper
+   */
+  import { global as globalThis } from '@storybook/global';
+  // @ts-ignore
+  const Button = globalThis.Components?.Button;
+
+  /**
+   * Rounds the button
+   */
+  export let primary: boolean = false;
+
+  /**
+   * Displays the count
+   */
+  export let count: number = 0;
+
+  /**
+   * Button text
+   * @slot
+   */
+  export let text: string = 'You clicked';
+
+  function handleClick(_event: MouseEvent) {
+    count += 1;
+  }
+</script>
+
+<h1>Button TypeScript</h1>
+
+<Button {primary} on:click on:click={handleClick} label="{text}: {count}" />
+
+<p>A little text to show this is a view.</p>
+<p>If we need to test components in a Svelte environment, for instance to test slot behaviour,</p>
+<p>then wrapping the component up in a view</p>
+<p>made just for the story is the simplest way to achieve this.</p>

code/frameworks/svelte-vite/template/stories_svelte-vite-default-ts/ts-docs.stories.js

@@ -0,0 +1,12 @@
+import ButtonTypescript from './ButtonTypeScript.svelte';
+
+export default {
+  title: 'stories/renderers/svelte/ts-docs',
+  component: ButtonTypescript,
+  args: {
+    primary: true,
+  },
+  tags: ['autodocs'],
+};
+
+export const Primary = {};

code/frameworks/sveltekit/template/stories_svelte-kit-skeleton-ts/ButtonTypeScript.svelte

@@ -0,0 +1,38 @@
+<script lang="ts">
+  /**
+   * @component Button TypeScript
+   * @wrapper
+   */
+  import { global as globalThis } from '@storybook/global';
+  // @ts-ignore
+  const Button = globalThis.Components?.Button;
+
+  /**
+   * Rounds the button
+   */
+  export let primary: boolean = false;
+
+  /**
+   * Displays the count
+   */
+  export let count: number = 0;
+
+  /**
+   * Button text
+   * @slot
+   */
+  export let text: string = 'You clicked';
+
+  function handleClick(_event: MouseEvent) {
+    count += 1;
+  }
+</script>
+
+<h1>Button TypeScript</h1>
+
+<Button {primary} on:click on:click={handleClick} label="{text}: {count}" />
+
+<p>A little text to show this is a view.</p>
+<p>If we need to test components in a Svelte environment, for instance to test slot behaviour,</p>
+<p>then wrapping the component up in a view</p>
+<p>made just for the story is the simplest way to achieve this.</p>

code/frameworks/sveltekit/template/stories_svelte-kit-skeleton-ts/ts-docs.stories.js

@@ -0,0 +1,12 @@
+import ButtonTypescript from './ButtonTypeScript.svelte';
+
+export default {
+  title: 'stories/renderers/svelte/ts-docs',
+  component: ButtonTypescript,
+  args: {
+    primary: true,
+  },
+  tags: ['autodocs'],
+};
+
+export const Primary = {};

code/presets/svelte-webpack/src/svelte-docgen-loader.ts

@@ -5,6 +5,22 @@ import * as fs from 'fs';
 import { preprocess } from 'svelte/compiler';
 import { logger } from '@storybook/node-logger';
 
+/*
+ * Patch sveltedoc-parser internal options.
+ * Waiting for a fix for https://github.com/alexprey/sveltedoc-parser/issues/87
+ */
+const svelteDocParserOptions = require('sveltedoc-parser/lib/options.js');
+
+svelteDocParserOptions.getAstDefaultOptions = () => ({
+  range: true,
+  loc: true,
+  comment: true,
+  tokens: true,
+  ecmaVersion: 12,
+  sourceType: 'module',
+  ecmaFeatures: {},
+});
+
 // From https://github.com/sveltejs/svelte/blob/8db3e8d0297e052556f0b6dde310ef6e197b8d18/src/compiler/compile/utils/get_name_from_filename.ts
 // Copied because it is not exported from the compiler
 function getNameFromFilename(filename: string) {
@@ -73,27 +89,30 @@ export default async function svelteDocgen(this: any, source: string) {
 
   let docgen = '';
 
+  let componentDoc: any;
   try {
     // FIXME
     // @ts-expect-error (Converted from ts-ignore)
-    const componentDoc = await svelteDoc.parse(options);
+    componentDoc = await svelteDoc.parse(options);
+  } catch (error) {
+    componentDoc = { keywords: [], data: [] };
+    if (logDocgen) {
+      logger.error(error as any);
+    }
+  }
 
-    // get filename for source content
-    const file = path.basename(resource);
+  // get filename for source content
+  const file = path.basename(resource);
 
-    // populate filename in docgen
-    componentDoc.name = path.basename(file);
+  // populate filename in docgen
+  componentDoc.name = path.basename(file);
 
-    const componentName = getNameFromFilename(resource);
+  const componentName = getNameFromFilename(resource);
 
-    docgen = dedent`
+  docgen = dedent`
       ${componentName}.__docgen = ${JSON.stringify(componentDoc)};
     `;
-  } catch (error) {
-    if (logDocgen) {
-      logger.error(error as any);
-    }
-  }
+
   // inject __docgen prop in svelte component
   const output = source + docgen;
 

code/renderers/svelte/template/stories/args.stories.js

@@ -7,7 +7,7 @@ import {
   STORY_RENDERED,
 } from '@storybook/core-events';
 import { addons } from '@storybook/preview-api';
-import ButtonView from './views/ButtonView.svelte';
+import ButtonView from './views/ButtonJavaScript.svelte';
 
 export default {
   component: ButtonView,

code/renderers/svelte/template/stories/js-docs.stories.js

@@ -0,0 +1,11 @@
+import ButtonJavaScript from './views/ButtonJavaScript.svelte';
+
+export default {
+  component: ButtonJavaScript,
+  args: {
+    primary: true,
+  },
+  tags: ['autodocs'],
+};
+
+export const Primary = {};

code/renderers/svelte/template/stories/slot-decorators.stories.js

@@ -1,4 +1,4 @@
-import ButtonView from './views/ButtonView.svelte';
+import ButtonView from './views/ButtonJavaScript.svelte';
 import BorderDecoratorRed from './views/BorderDecoratorRed.svelte';
 import BorderDecoratorBlue from './views/BorderDecoratorBlue.svelte';
 import BorderDecoratorProps from './views/BorderDecoratorProps.svelte';

code/renderers/svelte/template/stories/svelte-mdx.stories.mdx

@@ -1,6 +1,6 @@
 import { global as globalThis } from '@storybook/global';
 import { Meta, Story, Canvas } from '@storybook/addon-docs';
-import ButtonView from './views/ButtonView.svelte';
+import ButtonView from './views/ButtonJavaScript.svelte';
 import BorderDecoratorRed from './views/BorderDecoratorRed.svelte';
 
 <Meta title="stories/renderers/svelte/svelte-mdx" />

code/renderers/svelte/template/stories/views/ButtonView.svelte → code/renderers/svelte/template/stories/views/ButtonJavaScript.svelte

@@ -4,7 +4,8 @@
    * @wrapper
    */
   import { global as globalThis } from '@storybook/global';
-  const Button = globalThis.Components.Button;
+  // @ts-ignore
+  const Button = globalThis.Components?.Button;
 
   /**
    * Rounds the button

code/yarn.lock

@@ -8061,6 +8061,7 @@ __metadata:
     "@types/node": ^18.0.0
     magic-string: ^0.30.0
     svelte: ^4.0.0
+    svelte-preprocess: ^5.0.4
     sveltedoc-parser: ^4.2.1
     ts-dedent: ^2.2.0
     typescript: ~4.9.3