Bun vs Node JS: Features and Performance

Created: 12 September, 2023 by Yoan Arnaudov • Updated: 14 September, 2023 • Category: JavaScript

Bun vs Node JS: Features and Performance banner

Just a few days ago, Bun was released - Bun v1.0 - the first stable version.

The JS community has been really active these last few days. People are playing around with Bun, testing, and doing benchmarks.

Bun goal is to replace Node.js, and it claims that it's better, faster, and simpler to use. It reduces complexity by having a lot of tools built-in.

In this post, I'll compare the two and outline their pros and cons.

First of all, what is Bun?

Bun is a JavaScript Runtime, but it's not only that. It's an all-in-one tool for running, building, testing, and debugging server-side JavaScript and TypeScript. It is designed to be a drop-in replacement for Node.js. Its goal is to make development easier and make apps faster and simpler. It comes with a lot of stuff baked in.

For an in-depth Bun introduction, you can read my post - What is Bun and why it's here to stay.

Stability

First, let's start with the obvious one - stability. Bun reached a significant milestone a few days ago - its first stable release.

Node.js has been around for quite some time - its release date was back in 2009, and it's been 14 years since its release.

This definitely gives Node.js an advantage. Node.js reached maturity quite some time ago, and it's definitely production ready.

Bun, on the other hand, was released a few days ago, and you can be sure that bugs are yet to be discovered. I would not recommend using Bun in production for now. I would wait a few months before jumping on board.

Node.js wins the stability category

ECMAScript support

In terms of ECMAScript API support, we can say that both support the latest specs.

Since both are using popular runtimes - Chrome V8 and Safari WebKit, they have to be up to date because they run on millions of browsers.

ECMAScript category is a tie

API support

Bun has a small set of native APIs, mostly for IO. bun:sqlite is an interesting one.

Additionally, it has many of the Web APIs implemented, like fetch or Worker. 

And since Bun aims to be a drop-in replacement for Node.js - it has excellent support for Node.js APIs - most of which are already implemented or are work in progress. Visit the Node.js compatibility page for more information.

Here, I would give a slight advantage to Bun

Tooling

Bun is not only a JavaScript runtime. It's more of an all-in-one toolkit for building JavaScript apps. Something like a JavaScript Swiss knife.

Bun comes with these tools baked in the binary itself:

  • npx - Bun has bunx, which is also 5x faster
  • nodemon - Bun has a built-in watch mode
  • tsc, babel, ts-node, tsx - Bun can run .js, .ts, .cjs, .mjs, .jsx, and .tsx
  • esbuilt, webpack, parcel, rollup - Bun has a JavaScript bundler with esbuilt compatible plugin API
  • npm, yarn, .npmrc, yarn.lock, package-lock.json - Bun has a npm compatible package manager that reads your package.json and writes to node_modules, just like any other js package manager
  • jest, ts-jest, vitest, jest-extended - Bun is a Jest-compatible test runner with support for mocking, snapshot testing, and code coverage

Node.js comes with the runtime only.

Bun is the clear winner here with a substantial margin.

TypeScript

Most people these days like to use TypeScript in their JS projects, and I totally understand them. Bun features a built-in TypeScript transpiler. Which makes using TypeScript a lot easier. 

Node.js, on the other hand, runs only regular JavaScript, so you'll need one additional step (transpiling) before running your TypeScript code.

Bun is the clear winner here, as it offers out-of-the-box support for TypeScript

Performance

Bun claims to be faster than Node.js in pretty much everything - from building, installing packages, testing, and handling a lot of HTTP traffic.

While I haven't personally tested the performance, people on the internet already did, and the results are promising (favoring Bun).

I'll keep this post updated with more performance comparisons once they come out.

I would say Bun is the winner in the performance category

Conclusion

Having competition is always a good thing. It challenges people to push themselves to create something better.

The programming world is no different than the physical world.

Node.js made a splash when it came out, but a few years later, it started to move slowly.

Bun comes with a new energy, and it's already making an impact.