Migrating to Bun: A Modern JavaScript Runtime

Date: 2025-12-07

Today I migrated this Eleventy-based blog from Node.js to Bun, and I'm impressed with the results. Bun is a modern JavaScript runtime that's been gaining traction as a faster, more efficient alternative to Node.js.

Why Bun?

Bun offers several compelling advantages:

• Speed: Significantly faster package installation and script execution
• All-in-one toolkit: Built-in bundler, transpiler, and package manager
• Drop-in replacement: Compatible with Node.js APIs and npm packages
• Modern by default: Native TypeScript and JSX support without configuration

The Migration Process

The migration was surprisingly straightforward. Here's what I changed:

1. GitHub Actions Workflow

Updated the CI/CD pipeline to use Bun instead of Node.js:

- name: Setup Bun
  uses: oven-sh/setup-bun@v2
  with:
    bun-version: latest

- name: Install dependencies
  run: bun install --frozen-lockfile

- name: Build with Eleventy
  run: bun run build

2. Lock File Replacement

Removed package-lock.json and generated bun.lock:

rm package-lock.json
bun install

3. Package.json Cleanup

Removed the "type": "commonjs" field, as it's not needed with Bun.

Results

The migration took just a few minutes, and everything works seamlessly. Installation is noticeably faster, and the development experience remains identical since Eleventy runs the same way regardless of the runtime.

Local Development

Now you can use Bun commands:

# Install dependencies
bun install

# Start dev server
bun start

# Build for production
bun run build

Conclusion

If you're running a Node.js project and want to experiment with better performance, Bun is worth trying. The migration is low-risk since you can always switch back, but the speed improvements might convince you to stay.

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