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Arnav Chauhan
Arnav Chauhan

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Bun 1.0 , is the Hype Justified?

Bun.js is a new JavaScript runtime that was released in v1.0 in September 2023. It has been met with a lot of hype, with some people calling it the "future of JavaScript." But is the hype justified?

I came across Bun.js in a video back in July of 2022 and it read that it was going to be the fastest runtime. I dismissed it at that time as another Javascript framework like Deno without looking much into it. But with version 1.0 out with the benchmarks and a small hands on preview I have defiantly changed my mind. Fun fact first commit to Bun was done on 18 April 2021.

Bun.js Github repo

Bun.js Introduction

Fundamentally, Bun.js is a server-side JavaScript runtime similar to Node. A bundler/transpiler and a package management are built on top of this. Unlike Node, which uses the V8 engine, Bun is designed from the ground up using the WebKit/Safari JavaScriptCore engine. It does not diverge from Node. The libraries are created using C and Zig, and they specifically avoid relying on Node or NPM, reducing the amount of JavaScript in their stack. All of these choices are made to maximize performance. Huge performance improvements result by rewriting all JavaScript-implemented APIs, such as network and disk IO, in a lower level language.

There are many features Bun provides, but to get started we should take note of the following features(taken from official documentation):

  • In bun.js, every file is transpiled. TypeScript & JSX are simple to use out of the box without any configration
  • bun.js automatically loads environment variables from .env files
  • Web APIs like fetch, WebSocket, and ReadableStream are builtin
  • Node-API bun.js implements most of Node-API (N-API). Many Node.js native modules work out of the box.
  • node:fs node:path bun.js natively supports a growing list of Node.js core modules along with globals like Buffer and process
  • Bun's plugin API is universal, meaning it works for both the bundler and the runtime.

Bun is Fun

Where Bun has all the Fun

  1. Rapid startup: Bun.js starts up incredibly quickly, usually in less than one millisecond. This makes it perfect for applications that require responsiveness and for running on low-powered devices.
  2. Better DX : Another thing we need to talk about though is the bun package manager that's up to 25 times faster than NPM. And it's actually a standalone tool that can be used in any no Js project today.

  3. Small memory footprint: The memory footprint of Bun.js is typically 10MB or less. It is therefore perfect for programs that must be memory-efficient.

  4. Minimal API surface area: Bun.js has a small number of APIs, making it simple to understand and utilize.

  5. Bun.js's support for WebAssembly enables it to execute code that has been compiled into native machine code. This can dramatically boost some applications' performance.

Bun Developer expirience

Developer experience plays a big role in any framework or library that is out there. And I was shocked at how simple it is to work with bun, and how is support JSX out of the box.

Here is an example code for a simple JSX preview hello world website.

  fetch(req: Request) {
    return new Response(`<meta charset="UTF-8">
    <h1>Hello World from bun JSX 🤩</h1>
    `, {
        headers: {
            'Content-Type': 'text/html',
  error(error: Error) {
    return new Response("Oops \n" + error.toString(), { status: 500 });
  port: 4000
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Overall, I am very impressed with Bun.js. It is a promising new JavaScript runtime that has a lot of potential. I believe that it is worth trying out if you are looking for a fast, efficient, and easy-to-use JavaScript runtime.

I hope this blog post was helpful! Do checkout the official website to learn more about Bun.js, please visit the official website:

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