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bun-react-ssr

Imported from https://github.com/secondsky/claude-skills.

Packaged view

This page reorganizes the original catalog entry around fit, installability, and workflow context first. The original raw source lives below.

Stars

Hot score

Updated

March 20, 2026

Overall rating

C4.9

Composite score

4.9

Best-practice grade

B76.0

Install command

npx @skill-hub/cli install secondsky-claude-skills-bun-react-ssr

Repository

secondsky/claude-skills

Skill path: plugins/bun/skills/bun-react-ssr

Imported from https://github.com/secondsky/claude-skills.

Open repository

Best for

Primary workflow: Ship Full Stack.

Technical facets: Full Stack, Frontend.

Target audience: everyone.

License: Unknown.

Original source

Catalog source: SkillHub Club.

Repository owner: secondsky.

This is still a mirrored public skill entry. Review the repository before installing into production workflows.

What it helps with

Install bun-react-ssr into Claude Code, Codex CLI, Gemini CLI, or OpenCode workflows
Review https://github.com/secondsky/claude-skills before adding bun-react-ssr to shared team environments
Use bun-react-ssr for development workflows

Works across

Claude CodeCodex CLIGemini CLIOpenCode

Favorites: 0.

Sub-skills: 0.

Aggregator: No.

Original source / Raw SKILL.md

---
name: Bun React SSR
description: Use when building server-rendered React with Bun, including streaming SSR, hydration, renderToString, or custom SSR without a framework.
version: 1.0.0
---

# Bun React SSR

Build custom server-rendered React applications with Bun.

## Quick Start

```bash
# Initialize project
mkdir my-ssr-app && cd my-ssr-app
bun init

# Install dependencies
bun add react react-dom
bun add -D @types/react @types/react-dom
```

## Basic SSR Setup

### Server Entry

```typescript
// src/server.tsx
import { renderToString } from "react-dom/server";
import App from "./App";

Bun.serve({
  port: 3000,
  async fetch(req) {
    const url = new URL(req.url);

    // Serve static files
    if (url.pathname.startsWith("/static/")) {
      const file = Bun.file(`./public${url.pathname}`);
      if (await file.exists()) {
        return new Response(file);
      }
    }

    // Render React app
    const html = renderToString(<App url={url.pathname} />);

    return new Response(
      `<!DOCTYPE html>
      <html>
        <head>
          <meta charset="utf-8">
          <meta name="viewport" content="width=device-width, initial-scale=1">
          <title>React SSR</title>
        </head>
        <body>
          <div id="root">${html}</div>
          <script src="/static/client.js"></script>
        </body>
      </html>`,
      {
        headers: { "Content-Type": "text/html" },
      }
    );
  },
});

console.log("Server running on http://localhost:3000");
```

### Client Entry

```tsx
// src/client.tsx
import { hydrateRoot } from "react-dom/client";
import App from "./App";

hydrateRoot(
  document.getElementById("root")!,
  <App url={window.location.pathname} />
);
```

### React App

```tsx
// src/App.tsx
interface AppProps {
  url: string;
}

export default function App({ url }: AppProps) {
  return (
    <div>
      <h1>React SSR with Bun</h1>
      <p>Current path: {url}</p>
      <button onClick={() => alert("Hydrated!")}>Click me</button>
    </div>
  );
}
```

## Build Client Bundle

```typescript
// build.ts
await Bun.build({
  entrypoints: ["./src/client.tsx"],
  outdir: "./public/static",
  target: "browser",
  minify: true,
  splitting: true,
});
```

```bash
# Build client
bun run build.ts

# Start server
bun run src/server.tsx
```

## Streaming SSR

```tsx
// src/server-streaming.tsx
import { renderToReadableStream } from "react-dom/server";
import App from "./App";

Bun.serve({
  port: 3000,
  async fetch(req) {
    const url = new URL(req.url);

    const stream = await renderToReadableStream(
      <App url={url.pathname} />,
      {
        bootstrapScripts: ["/static/client.js"],
        onError(error) {
          console.error(error);
        },
      }
    );

    // Wait for shell to be ready (Suspense boundaries)
    await stream.allReady;

    return new Response(stream, {
      headers: { "Content-Type": "text/html" },
    });
  },
});
```

### With Suspense

```tsx
// src/App.tsx
import { Suspense } from "react";

function SlowComponent() {
  // This would be a data fetching component
  return <div>Loaded!</div>;
}

export default function App({ url }: { url: string }) {
  return (
    <html>
      <head>
        <title>Streaming SSR</title>
      </head>
      <body>
        <div id="root">
          <h1>Fast Shell</h1>
          <Suspense fallback={<div>Loading...</div>}>
            <SlowComponent />
          </Suspense>
        </div>
      </body>
    </html>
  );
}
```

## Data Fetching

### Server-Side Data

```tsx
// src/server.tsx
import { renderToString } from "react-dom/server";
import { Database } from "bun:sqlite";
import App from "./App";

const db = new Database("data.sqlite");

Bun.serve({
  async fetch(req) {
    const url = new URL(req.url);

    // Fetch data server-side
    const users = db.query("SELECT * FROM users").all();

    const html = renderToString(
      <App url={url.pathname} initialData={{ users }} />
    );

    return new Response(
      `<!DOCTYPE html>
      <html>
        <head><title>SSR</title></head>
        <body>
          <div id="root">${html}</div>
          <script>
            window.__INITIAL_DATA__ = ${JSON.stringify({ users })};
          </script>
          <script src="/static/client.js"></script>
        </body>
      </html>`,
      { headers: { "Content-Type": "text/html" } }
    );
  },
});
```

### Client Hydration

```tsx
// src/client.tsx
import { hydrateRoot } from "react-dom/client";
import App from "./App";

const initialData = (window as any).__INITIAL_DATA__;

hydrateRoot(
  document.getElementById("root")!,
  <App url={window.location.pathname} initialData={initialData} />
);
```

## Routing

### Simple Router

```tsx
// src/Router.tsx
import { useState, useEffect } from "react";

interface Route {
  path: string;
  component: React.ComponentType;
}

interface RouterProps {
  routes: Route[];
  initialPath: string;
}

export function Router({ routes, initialPath }: RouterProps) {
  const [path, setPath] = useState(initialPath);

  useEffect(() => {
    const handlePopState = () => setPath(window.location.pathname);
    window.addEventListener("popstate", handlePopState);
    return () => window.removeEventListener("popstate", handlePopState);
  }, []);

  const route = routes.find((r) => r.path === path);
  const Component = route?.component || NotFound;

  return <Component />;
}

export function Link({ href, children }: { href: string; children: React.ReactNode }) {
  const handleClick = (e: React.MouseEvent) => {
    e.preventDefault();
    window.history.pushState({}, "", href);
    window.dispatchEvent(new PopStateEvent("popstate"));
  };

  return <a href={href} onClick={handleClick}>{children}</a>;
}

function NotFound() {
  return <h1>404 - Not Found</h1>;
}
```

## CSS Handling

### Inline Styles

```tsx
const html = renderToString(<App />);

return new Response(
  `<!DOCTYPE html>
  <html>
    <head>
      <style>${await Bun.file("./src/styles.css").text()}</style>
    </head>
    <body>
      <div id="root">${html}</div>
    </body>
  </html>`,
  { headers: { "Content-Type": "text/html" } }
);
```

### External Stylesheet

```tsx
// Build CSS
await Bun.build({
  entrypoints: ["./src/styles.css"],
  outdir: "./public/static",
});

// Link in HTML
`<link rel="stylesheet" href="/static/styles.css">`
```

## Development Setup

### Hot Reload Development

```typescript
// dev.ts
import { watch } from "fs";

const srcDir = "./src";
let serverProcess: Subprocess | null = null;

async function startServer() {
  serverProcess?.kill();
  serverProcess = Bun.spawn(["bun", "run", "src/server.tsx"], {
    stdout: "inherit",
    stderr: "inherit",
  });
}

// Watch for changes
watch(srcDir, { recursive: true }, async (event, filename) => {
  console.log(`Change detected: ${filename}`);
  await startServer();
});

await startServer();
console.log("Dev server watching...");
```

## Production Build

```typescript
// build-prod.ts

// Build client
await Bun.build({
  entrypoints: ["./src/client.tsx"],
  outdir: "./dist/public/static",
  target: "browser",
  minify: true,
  splitting: true,
  sourcemap: "external",
});

// Build server
await Bun.build({
  entrypoints: ["./src/server.tsx"],
  outdir: "./dist",
  target: "bun",
  minify: true,
});

console.log("Build complete!");
```

## Common Errors

| Error | Cause | Fix |
|-------|-------|-----|
| `Hydration mismatch` | Server/client HTML differs | Check initial state |
| `document is not defined` | SSR accessing DOM | Guard with typeof window |
| `Cannot use hooks` | Hooks outside component | Check component structure |
| `Flash of unstyled content` | CSS not loaded | Inline critical CSS |

## Performance Tips

1. **Use streaming SSR** for faster TTFB
2. **Inline critical CSS** above the fold
3. **Code split** client bundle
4. **Cache rendered HTML** for static pages
5. **Use Suspense** for progressive loading

## When to Load References

Load `references/streaming-patterns.md` when:
- Complex Suspense boundaries
- Selective hydration
- Progressive enhancement

Load `references/caching.md` when:
- HTML caching strategies
- CDN integration
- Edge rendering