The Bun is Fresh out of the Oven! * Mariya Baig

4 min readSep 15, 2023

In the tech world, there’s a new player in town, and it’s causing quite a stir. Meet Bun, an open-source project that has recently hit the 1.0 milestone. But you might be wondering, “What’s all the fuss about? Do we really need another tool?”

To answer that question, let’s first dive into why Bun has garnered so much attention. The JavaScript landscape has seen remarkable changes over the past 15 years, thanks to factors like regular ECMAScript updates, the meteoric rise of TypeScript, and the widespread adoption of JSX. These transformations have compelled JavaScript runtimes to evolve, with a focus on delivering faster and more streamlined performance.

Bun’s Promise

Bun isn’t just another tool; it offers compelling advantages over established options like Node.js and Deno. It’s core promise is to reduce tooling complexity without compromising what developers cherish about JavaScript.

Picture setting up a REST API server in today’s development landscape. You’d typically use Node.js for runtime, nodemon for watching changes, transpilers like tsc for TypeScript, npm for package management, and jest for testing. Enter Bun, which streamlines this process by eliminating the need for multiple tools:

Node.js Not Required: With Bun, you can say goodbye to Node.js; it’s no longer a prerequisite.
Built-In Watch Mode: It comes with its own built-in watch mode, obviating the need for nodemon or similar tools.
Automatic .env Support: It reads .env files by default, eliminating the need for dotenv or cross-env.
Support for Various File Types: It can run various file types, including .js, .ts, .cjs, .mjs, .jsx, and .tsx. This means you can skip installing tools like babel, tsc, ts-node, and tsx in your projects.
Powerful Bundler: Acting as a JavaScript bundler, Bun delivers exceptional performance. It’s even compatible with esbuild plugins, allowing you to avoid using esbuild, webpack, or parcel.
Swift Package Management: When it comes to speed, Bun shines. It functions like npm and yarn, with familiar commands, but it’s a whopping 30 times faster. It understands your package.json file and writes to node_modules rapidly.
Built-In Testing: Bun includes a built-in test runner that’s compatible with Jest, enabling you to write unit tests without additional dependencies.

Written in Zig and Powered by JavaScriptCore :The Tech Behind Bun

At its core, Bun is a JavaScript Runtime. But what does that mean in simpler terms? Let’s break it down:

The Engine: A runtime includes an engine, which executes JavaScript code. While V8 is a well-known engine powering Chrome and NodeJS, Bun uses a different one: JavaScriptCore.
JavaScriptCore: This high-performance solution, developed by Apple for the Safari Browser, prioritizes speed .
The Runtime: A JavaScript engine can’t work in isolation. It collaborates with external APIs, message queues, and the familiar Event Loop to create a JavaScript Runtime.

In Bun’s case, this entire process is meticulously crafted from scratch using Zig, a low-level, versatile language similar to C or Rust, known for high-performance application development.

This approach not only boosts performance but also enhances memory management during startup and runtime. Combined with its commitment to delivering exceptional speed, Bun emerges as a strong alternative to challenge NodeJS.

Bun makes working with TypeScript a breeze. You can directly run your TypeScript modules without going through an additional compilation step. This simplifies your build process because you don’t have to worry about converting TypeScript to JavaScript; it’s already taken care of.

Bun introduces what we call “consistent module imports.” This means you can use both import {} from 'file' and require('module') in your modules, even mixing them in the same file. Everything works seamlessly, eliminating the need to configure and maintain a consistent module resolution approach throughout your codebase.

Bun comes with a default watch mode that lets you run your applications. This allows you to see live changes in your applications as they happen, no additional configuration or package installation required. Bun boosts developer efficiency through this hot reloading functionality. By executing Bun with the ‘-hot’ option, you can activate hot reloading, which guarantees that your application refreshes automatically upon file modifications. This capability reduces downtime and optimizes your coding workflow. This is unlike NodeJS, where you often need to install packages like nodemon for watch mode. Bun simplifies your workflow by eliminating the need for such setup in your future projects.

Bun offers its own set of internal APIs, distinct from NodeJS core APIs. While they provide the same functionality, Bun’s APIs are more elegant and straightforward compared to NodeJS. For instance, Bun.serve({}) allows you to quickly create a server with far less code than you’d need in NodeJS. It also provides more elegant file reading and writing APIs compared to NodeJS.

It seamlessly integrates with widely used server frameworks like Express, Koa, and Hono. Moreover, it effortlessly supports applications built using prominent full-stack frameworks like Next.js, Remix, Nuxt, Astro, SvelteKit, Nest, SolidStart, and Vite. These assessments cover various critical aspects of the Node.js API surface, ensuring Bun’s compatibility and reliability.

How to start using Bun?

Install Bun v1.0.1

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

Quickstart your journey here.

The Future of Bun

Does this mean you should immediately replace NodeJS with Bun? Not necessarily. Adoption of new technologies takes time, and many developers prefer gradual transitions. Additionally, there are some limitations to using Bun:

In conclusion, Bun offers exciting possibilities for JavaScript development. While widespread adoption may take time, it’s worth exploring to see how it can enhance your workflow. What are your thoughts on Bun? Do you think it could eventually replace NodeJS and npm?

Originally published at https://mariyabaig.com on September 15, 2023.