In this article we examine whether Bun is ready to take on Node.js, exploring its strengths such as performance and potential challenges due to its smaller ecosystem.

Bun was introduced in November 2023, and its ambitious goal was to outperform Node.js. As a new JavaScript runtime, Bun focuses on enhanced speed and performance, leveraging the JavaScriptCore engine for a superior startup time compared to Node.js's V8 engine. Offering elegant APIs and a comprehensive developer toolkit, Bun is designed as a drop-in replacement, promising efficiency and productivity.

Does Bun Really Affect Node.js?

Even on the Bun webpage, emphasis is placed on the fact that this runtime is purposefully designed as a drop-in substitute for Node.js.
It inherently integrates numerous Node.js and Web APIs, encompassing [fs], [path], [Buffer], and others.

Bun aims to execute most of the world's server-side JavaScript while furnishing tools to enhance performance, simplify complexities, and amplify developer productivity. One of the reasons why Bun is considered faster than Node.js is because it uses the JavaScriptCore engine, while Node.js uses the JavaScript V8 engine. The former has been optimized for faster startup time.
Additionally, by supporting Node-style module resolution, Bun aims to achieve complete compatibility with the built-in Node.js globals (such as process, Buffer) and modules (like path, fs, http, etc.). This is an ongoing effort that remains incomplete. You can refer to the compatibility page on Bun for the current status.

Deno as an Alternative?

Choosing between Bun and Node.js shouldn't be seen as the only option available. In 2018, Deno emerged as a Rust-based JavaScript runtime, aiming to improve upon Node.js features.

Deno is specifically designed to provide enhanced support for JSX and TypeScript, aligning more closely with web standards. Additionally, it simplifies deployment by packaging applications as self-contained executables.

For prioritizing security, Deno is an excellent choice; if speed is a priority, Bun might be more suitable.