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Bun 1.0 – Testing a Turbo-Fast JS Runtime

#bun#javascript#tooling

Bun 1.0 is out. It's a new JavaScript runtime built in Zig, and it aims to be fast—very fast.

It’s not just a runtime. It also includes:

  • A bundler
  • A test runner
  • A package manager
  • A development server

All built in.

Bun tries to replace several tools at once: Node, Webpack, Jest, even npm.

Installing Bun

To install Bun:

curl https://bun.sh/install | bash

You get access to the bun command, which works like node, npm, and vite—all at once.

Creating a Bun project

You can start a new project like this:

bun init

Then run your server:

bun run index.ts

Bun supports TypeScript out of the box—no config, no transpile step.

Why it’s interesting

  • Bun uses JavaScriptCore (from Safari), not V8
  • Written in Zig, so it compiles to a single binary
  • It's fast—cold starts and installs are much quicker than Node

What I tried

I migrated a simple server from Node to Bun:

// index.ts
export default {
  port: 3000,
  fetch(request: Request) {
    return new Response("Hello from Bun!");
  },
};

Then ran:

bun run index.ts

Worked instantly.

Install times for dependencies were about 10x faster than npm.

Gotchas

  • Not all Node APIs are supported
  • Still new—some ecosystem gaps
  • No Windows support at the time of writing

Should you use it?

Bun is promising. It’s great for:

  • Simple scripts
  • Side projects
  • Trying something fast and new

For large teams, the Node ecosystem is still more mature. But Bun is improving fast.