Bun and Node.js are two JavaScript runtime technologies to run JavaScript on the server. Node.js is the undisputed king of server-side development with JavaScript, but Bun has gained popularity thanks to its unbelievable performance capabilities. The real question is, though: does it really make sense to use Bun instead of Node.js?

Let's learn about Bun and Node.js, dig into their characteristics, and explore some scenarios where Bun can be a better alternative to Node.js.

Join us on this journey to discover what Bun offers compared to Node.js!

What Are Bun and Node.js?

Bun is a new JavaScript runtime designed for server-side execution of both JavaScript and TypeScript. It’s developed in Zig, a low-level programming language that allows Bun to reach extreme levels of performance. Thanks to that, it’s suitable for developing high-speed server applications.

Node.js is the most popular JavaScript runtime for server-side development. It’s supported by a vast ecosystem of npm packages and a community of millions of users. That’s helped Node.js become widely used for building web applications, APIs, and backends.

Bun and Node.js are both JavaScript runtimes. At the same time, while they both provide the ability to run JavaScript on the server, they differ in their core focus and characteristics.

Bun and Node.js: Pros and Cons

To better understand when to use Bun over Node.js, you first need to look at the benefits and drawbacks of the two technologies. This will help you to see which is the best option in specific scenarios.

Let’s jump into the pros and cons of Bun and Node.js!

Bun

👍 Pros:

• Extreme performance: Bun's core focus is on executing JavaScript as fast as possible.
• TypeScript support: Bun supports TypeScript natively and out of the box, with no additional configuration required.
• Node.js compatibility: It’s designed to integrate with existing Node.js codebases and npm libraries.

👎 Cons:

• Too new: Bun 1.0 was released on September 8th, 2023. This makes it relatively new, so there is a lack of documentation, questions over its stability, and a small community.
• Limited API: As a young technology, the roadmap still involves many key features.
• Zig popularity: Zig isn’t a popular language, which impacts community contributions.

Node.js

👍 Pros:

• Large community and ecosystem: Node.js can boast more than 25 million users and a million libraries.
• Highly stable: Since its first release in 2009, the technology has become mature and stable.
• Easy to use: Node.js wouldn’t have become so popular if its API wasn’t so intuitive.

👎 Cons:

• Doesn’t support TypeScript natively: Adding TypeScript requires extra dependencies and configurations.
• node_modules grows big: The folder used to install dependencies can easily reach gigabytes of space and hundreds of thousands of files.
• Not standard compliant: Node.js has only recently begun to adopt web standards such as Fetch API. Many have yet to be implemented.

5 Scenarios To Adopt Bun Over Node.js

Let's explore five scenarios (based on the above pros and cons) where Bun proves a better alternative to Node.js.

1. When Performance Is Key

In most cases, Bun is faster than Node.js. Zig offers great control over code execution, which allows maintainers to optimize for performance at a low level. Bun is also based on the fast and efficient JavaScriptCore engine. In contrast, Node.js is written in less efficient JavaScript and relies on the slower V8 JavaScript engine.

At the time of writing, Bun processes start 4x faster than Node.js. Plus, the npm-compatible package manager provided by Bun is 25x faster than npm install. Speed is one of the project's design goals, as you can see by running the benchmarks in the official repository.

2. When You Want an All-in-One Solution

Bun is a complete toolkit for building JavaScript apps. In particular, it includes:

• bun run: A CLI command to execute JavaScript/TypeScript files.
• bun install: A Node.js-compatible package manager designed to be a faster replacement for npm and yarn.
• bun test: A built-in, fast, Jest-compatible test runner to execute tests with the Bun runtime.
• Bun.build: A native bundler to build server-side JavaScript applications efficiently. At the time of writing, it’s still in beta.

Thanks to its built-in test runner, bundler, and package manager, Bun provides a cohesive developer experience. This ensures consistency and efficiency throughout the software development process.

3. When Module Resolution Might Become a Problem

Module resolution in JavaScript is a complex topic, as CommonJS and ES modules don't always easily coexist. The Node.js ecosystem is built on CommonJS. It has been difficult to add support for ES modules. The problem is that interoperating between the two module systems brings large challenges. On top of that, TypeScript enforces its own set of rules around imports. That's why the transition from require() to import instructions is taking years.

Bun aims to provide a consistent module resolution system that just works. Some game-changing features offered by this system are:

• Import paths can optionally include extensions.
• You can import any file or package, even .cjs files.
• You can require() any file or package, even .ts or .mjs files.
• You can use require() and import statements in the same file.

That greatly simplifies module resolution, saving time in making libraries work together.

4. When You Need an Efficient Built-In Internal Database

SQLite is a popular self-contained, serverless, and zero-configuration SQL database engine. Its embeddable nature makes it an excellent choice as an internal database. It enables you to manage structured data without the complexity of traditional databases.

If you're building a web application that requires an internal database and want to limit external dependencies, Bun is a great option. It comes with a built-in bun:sqlite module, a high-performance implementation of an SQLite3 driver. Its API is inspired by the popular better-sqlite3, but bun:sqlite guarantees from 3 to 6 times better performance.

5. When You Want to Be Able to Switch to Node.js

Bun is still an immature technology, but that shouldn't discourage you from using it. For sure, as your project grows big, the need for a more stable and widely-known technology like Node.js may arise. But thanks to Bun's goal of becoming fully compatible with Node.js, that's not a big problem. Bun is designed as a drop-in replacement for Node.js, and transitioning from one to the other is a relatively smooth process.

Starting with Bun gives you access to its modern features and high-performance advantages. If, one day, you need Node.js, you can switch your codebase with little effort. This flexibility ensures that your project can evolve and adapt to changing requirements. Thus, Bun is an attractive choice not only for its immediate benefits but also for long-term maintainability goals.

Wrapping Up

In this blog post, we looked at why and when Bun can be a good replacement for Node.js.

You now know:

• About Node.js and Bun, and why they can be compared
• The pros and cons of Bun
• The pros and cons of Node.js
• Five scenarios where Bun is a better choice than Node.js

Thanks for reading!

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P.P.S. If you need an APM for your Node.js app, go and check out the AppSignal APM for Node.js.