Bun, A Revolution

What's Bun ?

Bun is a fresh out of the oven new runtime for JavaScript, just like NodeJS or Deno, you might know them. Now, you might know Deno already tries to solve some of the problems NodeJS has, but it's not enough. Bun not only solves all of our problems, but it also brings a lot of new features to the table.

Bun's runtime and its features

Bun 1.0 just dropped, and it's the reason for this blog post. Just know that I'm not really a guy that likes to switch to shiny new things, for example, Deno is out for a while now, but before Bun I was still using NodeJS. So you can trust me when I say that Bun's not just another shiny new thing, it's actually a revolution.

What's the problem with Node ?

You might ask, what's the problem with Node ? Yes it does work, but think of all the dependencies. Your package manager, npm is very slow, so you switched to pnpm. Because node doesn't have a watch feature you use nodemon (Yes I know Node 21 has a watch feature, but Node is only slowly catching up after years). You need env variables, you use dotenv. You need a bundler, so you use esbuild. You're building a big app and you want typescript, you use typescript tsc. You need tests, and install vitest.

Can you believe that ? For a normal project you would use 6 different tools, and that might not even be all of them. That's because until recently, Node didn't understand people would actually like their tools to be bundled directly.

Bun to the rescue

Yes! Bun is here to save us from all of this. And trust me, it will be easy. Virtually any application can just be run with bun. Just replace node with bun, npm with bun and that's it. Bun 1.0 is compatible with most of the popular fullstack frameworks, and server frameworks such as Express, Koa or Hono. Bun is so fast because it doesn't use the v8 engine, it uses the JavaScript core from Webkit, which is known to be faster than v8. Also, Bun is written in Zig, which is a low-level language that is roughly as fast as C++.

ESM & CommonJS compatibility

You might know the old school require syntax, which is CommonJS and is still used a lot today, but also the new ES Modules syntax, which is a lot more modern using the import syntax. You might've ran into plenty of errors when trying to use both in the same project, such as trying to require Chalk 5 :

That's because chalk v5 uses ES Modules, and you're trying to use it with CommonJS. Yeah I know, it's a mess. But Bun solves this problem. Yes, you heard it right, Bun is compatible with both CommonJS and ES Modules, and you can use them both in the same project. For some people, this might be just another feature, but for some others, this will be a life saver.

Web APIs

Bun provides support for the Web Standard APIs that are availab le in browsers, such as fetch, Request, Response, WebSocket, ReadableStream...

You don't need to install any package, Bun's APIs are in native code directly. This means you don't need to import anything it just works, like on the web.

Hot reloading

It's not just hot reloading. Nodemon restarts the whole process when a change is detected, which is slow and not very efficient. Bun reloads your code without restarting the process, which is a lot faster. This also means that HTTP and WebSocket connections are not closed when you reload your code, which is a lot more convenient when you're working on a web app and testing things. State doesn´t change.

Bun's native APIs

Bun provides its own native APIs for thing such as the equivalent of fs in NodeJS. For example, in Bun, this is how you treat files :

Bun is said to read files 10x faster than NodeJS, and write files 3x faster than NodeJS.

You can also serve 4x faster HTTP servers with Bun still using the native APIs:

Bun's package managing

This is a part I'm really excited about. I often switch between computers to code, and I'm sure some you do too. I used to have a crappy laptop, and I had to wait many minutes to install packages. I switched to pnpm and it was a bit faster, but still slooow.

Bun's package manager is also called using bun, and it's so. much. faster. I just switched to Linux on my new laptop, and I had to reinstall packages for this project, and it was lightning-fast. Usually it's slow enough that I just watch a video while installing packages...

Install Bun Now

Bun is available on Windows, Linux and macOS! You can install Bun right now. Just run this command in your terminal :

• Windows
• Linux / macOS

Conclusion

I think everyone should start using Bun right now. There's no reason not to, it takes 2 minutes to setup, and it's faster. Trust me, even for things such as running scripts, the 150ms gained feel like it's 10x faster because it feels instant and not laggy. You can check out the Bun Website for more information about Bun.

Thanks for reading, and see you in the next one!