feat: ignore <style> tag content in markdown (#5)

## Summary

- Backport #3 to the v18 branch.
- Ignore `<style>` nodes during Markdown serialization so CSS content is
omitted from SSG-MD output.
- Add a regression test for `<style>` handling on React 18.

## Testing

- `pnpm install --frozen-lockfile`
- `pnpm test`
- `pnpm exec biome check .`
- `pnpm build`

Author: SoonIter

README.md

@@ -1,31 +1,143 @@
 # react-render-to-markdown
 
+[![npm version](https://img.shields.io/npm/v/react-render-to-markdown.svg)](https://www.npmjs.com/package/react-render-to-markdown)
+[![license](https://img.shields.io/npm/l/react-render-to-markdown.svg)](https://github.com/SoonIter/react-render-to-markdown/blob/main/LICENSE)
+
+Render React components to Markdown strings — like `renderToString` in `react-dom`, but outputs **Markdown** instead of HTML.
+
+Built on top of `react-reconciler`, this library creates a custom React renderer that traverses the React element tree and produces well-formatted Markdown. It follows **SSR-like behavior**: `useEffect`, `useLayoutEffect`, and `useInsertionEffect` are suppressed (as no-ops), while `useState`, `useMemo`, `useRef`, `useContext`, and other synchronous hooks work as expected.
+
+## Installation
+
+The major version of `react-render-to-markdown` follows the React version. Install the one that matches your project:
+
+```bash
+# React 19
+npm install react-render-to-markdown@19
+
+# React 18
+npm install react-render-to-markdown@18
+```
+
+## Quick Start
+
 ```tsx
 import { renderToMarkdownString } from 'react-render-to-markdown';
 
-const markdown = renderToMarkdownString(<h1>Hello, World!</h1>);
+const markdown = await renderToMarkdownString(<h1>Hello, World!</h1>);
 console.log(markdown); // # Hello, World!
 ```
 
-## Installation
+## Usage
 
-```bash
-npm install react-render-to-markdown
+### Basic HTML Elements
+
+```tsx
+import { renderToMarkdownString } from 'react-render-to-markdown';
+
+await renderToMarkdownString(
+  <div>
+    <strong>foo</strong>
+    <span>bar</span>
+  </div>,
+);
+// Output: '**foo**bar'
 ```
 
+### React Components & Hooks
+
+Synchronous hooks (`useState`, `useMemo`, `useRef`, `useContext`, etc.) work as expected. Client-side effects (`useEffect`, `useLayoutEffect`) are automatically suppressed:
+
+```tsx
+import { createContext, useContext, useMemo, useState } from 'react';
+import { renderToMarkdownString } from 'react-render-to-markdown';
+
+const ThemeContext = createContext('light');
+
+const Article = () => {
+  const [count] = useState(42);
+  const theme = useContext(ThemeContext);
+  const doubled = useMemo(() => count * 2, [count]);
+
+  return (
+    <>
+      <h1>Hello World</h1>
+      <p>Count: {count}, Doubled: {doubled}, Theme: {theme}</p>
+    </>
+  );
+};
+
+await renderToMarkdownString(
+  <ThemeContext.Provider value="dark">
+    <Article />
+  </ThemeContext.Provider>,
+);
+// Output:
+// # Hello World
+//
+// Count: 42, Doubled: 84, Theme: dark
+```
+
+### Code Blocks
+
+Fenced code blocks with language and title support:
+
+```tsx
+await renderToMarkdownString(
+  <pre data-lang="ts" data-title="rspress.config.ts">
+    <code>{'const a = 1;\n'}</code>
+  </pre>,
+);
+// Output:
+// ```ts title=rspress.config.ts
+// const a = 1;
+// ```
+```
+
+For languages that may contain triple backticks (like `markdown`, `mdx`, `md`), four backticks (``````) are automatically used as delimiters.
+
+## Supported Elements
+
+| HTML Element | Markdown Output |
+| --- | --- |
+| `<h1>` – `<h6>` | `#` – `######` headings |
+| `<p>` | Paragraph with trailing newlines |
+| `<strong>`, `<b>` | `**bold**` |
+| `<em>`, `<i>` | `*italic*` |
+| `<code>` | `` `inline code` `` |
+| `<pre>` + `<code>` | Fenced code block (` ``` `) |
+| `<a href="">` | `[text](url)` |
+| `<img>` | `![alt](src)` |
+| `<ul>`, `<ol>`, `<li>` | Unordered / ordered lists |
+| `<blockquote>` | `> blockquote` |
+| `<br>` | Line break |
+| `<hr>` | `---` horizontal rule |
+| `<style>` | Ignored |
+| `<table>`, `<thead>`, `<tbody>`, `<tr>`, `<th>`, `<td>` | GFM table |
+
+Any unrecognized elements (e.g. `<div>`, `<span>`, `<section>`) render their children as-is, acting as transparent wrappers.
+
+## How It Works
+
+1. **Custom React Reconciler** — Uses `react-reconciler` to build a lightweight tree of `MarkdownNode` objects from your React element tree.
+2. **SSR-like Hook Behavior** — Client-side effects (`useEffect`, `useLayoutEffect`, `useInsertionEffect`) are intercepted and turned into no-ops, matching React's Fizz server renderer behavior. This ensures browser-only code (e.g. `document`, `window`) in effects never runs.
+3. **Tree-to-Markdown Serialization** — The `MarkdownNode` tree is serialized to a Markdown string via a recursive `toMarkdown` function.
+
 ## Requirements
 
 ```json
 {
-  "react": "^18.2.0",
+  "react": ">=18.2.0",
   "react-reconciler": "^0.29.0"
 }
 ```
 
+> **Note:** React 18.2 or above is required. The effect-interception mechanism relies on React 18's internal hooks dispatcher (`__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED.ReactCurrentDispatcher.current`).
+
 ## Used By
 
-- [Rspress SSG-MD](https://rspress.rs/guide/basic/ssg-md) — Rspress uses this library to power its SSG-MD feature, which renders documentation pages as Markdown files instead of HTML. This enables Generative Engine Optimization (GEO) by generating `llms.txt` and `llms-full.txt` for better Agent accessibility.
+- [**Rspress SSG-MD**](https://rspress.rs/guide/basic/ssg-md) — Rspress uses this library to power its SSG-MD (Static Site Generation to Markdown) feature. SSG-MD renders documentation pages as Markdown files instead of HTML, generating `llms.txt` and `llms-full.txt` for [Generative Engine Optimization (GEO)](https://en.wikipedia.org/wiki/Generative_engine_optimization), enabling better accessibility for AI agents and large language models.
 
 ## License
 
-MIT License.
+[MIT](./LICENSE)

src/react/render.test.tsx

@@ -243,6 +243,28 @@ console.log('Hello, world!');
 });
 
 describe('renderToMarkdownString - styles', () => {
+  it('ignores style tag content', async () => {
+    expect(
+      await renderToMarkdownString(
+        <div>
+          <h1>Title</h1>
+          <style>{`
+            .rspress-doc {
+              color: red;
+            }
+          `}</style>
+          <p>Content</p>
+        </div>,
+      ),
+    ).toMatchInlineSnapshot(`
+      "# Title
+
+      Content
+
+      "
+    `);
+  });
+
   it('renders two row correctly', async () => {
     const Comp1 = () => {
       return (

src/react/render.ts

@@ -113,46 +113,47 @@ function toMarkdown(root: MarkdownNode): string {
   const { type, props, children } = root;
 
   // Get children's Markdown
-  const childrenMd = children
-    .map((child) => {
-      if (child instanceof TextNode) {
-        return child.text;
-      }
-      return toMarkdown(child);
-    })
-    .join('');
+  const childrenMd = () =>
+    children
+      .map((child) => {
+        if (child instanceof TextNode) {
+          return child.text;
+        }
+        return toMarkdown(child);
+      })
+      .join('');
 
   // Generate corresponding Markdown based on element type
   switch (type) {
     case 'root':
-      return childrenMd;
+      return childrenMd();
     case 'h1':
-      return `# ${childrenMd}\n\n`;
+      return `# ${childrenMd()}\n\n`;
     case 'h2':
-      return `## ${childrenMd}\n\n`;
+      return `## ${childrenMd()}\n\n`;
     case 'h3':
-      return `### ${childrenMd}\n\n`;
+      return `### ${childrenMd()}\n\n`;
     case 'h4':
-      return `#### ${childrenMd}\n\n`;
+      return `#### ${childrenMd()}\n\n`;
     case 'h5':
-      return `##### ${childrenMd}\n\n`;
+      return `##### ${childrenMd()}\n\n`;
     case 'h6':
-      return `###### ${childrenMd}\n\n`;
+      return `###### ${childrenMd()}\n\n`;
     case 'p':
-      return `${childrenMd}\n\n`;
+      return `${childrenMd()}\n\n`;
     case 'strong':
     case 'b':
-      return `**${childrenMd}**`;
+      return `**${childrenMd()}**`;
     case 'em':
     case 'i':
-      return `*${childrenMd}*`;
+      return `*${childrenMd()}*`;
     case 'code':
       // When <code> is nested inside <pre>, it represents the code block body,
       // so we must not wrap it with inline backticks (would create nested fences).
       if (root.parent?.type === 'pre') {
-        return childrenMd;
+        return childrenMd();
       }
-      return `\`${childrenMd}\``;
+      return `\`${childrenMd()}\``;
     case 'pre': {
       const _language =
         props['data-lang'] || props.language || props.lang || '';
@@ -163,33 +164,35 @@ function toMarkdown(root: MarkdownNode): string {
         ? '````'
         : '```';
 
-      return `\n${block}${language}${title ? ` title=${title}` : ''}\n${childrenMd}\n${block}\n`;
+      return `\n${block}${language}${title ? ` title=${title}` : ''}\n${childrenMd()}\n${block}\n`;
     }
     case 'a':
-      return `[${childrenMd}](${props.href || '#'})`;
+      return `[${childrenMd()}](${props.href || '#'})`;
     case 'img':
       return `![${props.alt || ''}](${props.src || ''})`;
     case 'ul':
-      return `${childrenMd}\n`;
+      return `${childrenMd()}\n`;
     case 'ol':
-      return `${childrenMd}\n`;
+      return `${childrenMd()}\n`;
     case 'li': {
       const isOrdered = root.parent && root.parent.type === 'ol';
       const prefix = isOrdered ? '1. ' : '- ';
-      return `${prefix}${childrenMd}\n`;
+      return `${prefix}${childrenMd()}\n`;
     }
     case 'blockquote':
-      return `> ${childrenMd.split('\n').join('\n> ')}\n\n`;
+      return `> ${childrenMd().split('\n').join('\n> ')}\n\n`;
     case 'br':
       return '\n';
     case 'hr':
       return '---\n\n';
+    case 'style':
+      return '';
     case 'table':
-      return `${childrenMd}\n`;
+      return `${childrenMd()}\n`;
     case 'thead':
-      return childrenMd;
+      return childrenMd();
     case 'tbody':
-      return childrenMd;
+      return childrenMd();
     case 'tr': {
       const cells = children
         .filter((child): child is MarkdownNode => child instanceof MarkdownNode)
@@ -205,9 +208,9 @@ function toMarkdown(root: MarkdownNode): string {
     }
     case 'th':
     case 'td':
-      return childrenMd;
+      return childrenMd();
     default:
-      return childrenMd;
+      return childrenMd();
   }
 }