Friday, May 24, 2024

An Introduction to the Bun JavaScript Runtime — SitePoint

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A rival JavaScript runtime contender has entered the battle between Node.js and Deno. On this article, we take a primary take a look at Bun, and the explanations it could tempt you away out of your present favourite.

Ryan Dahl launched Node.js in 2009. It wasn’t the primary server-side JavaScript runtime, however Node.js quickly gained momentum. Model 20 arrived in 2023, and Node.js has the most important growth ecosystem, with 3.2 million modules — accounting for nearly 500 billion downloads per week (in response to

In 2020, Ryan Dahl launched Deno — a remix of “noDe” — to modernize JavaScript growth and tackle legacy points with Node.js safety, API compatibility, tooling, and module administration. Reception has been constructive, though Deno is but to problem Node’s domination.

In 2022, Jarred Sumner launched Bun following his frustrations with the velocity of Node.js when growing a Subsequent.js undertaking. The origin of the title is unclear, and the emblem doesn’t assist! It might relate to the meals, fluffy rabbits, “bundle”, or maybe it’s a brief, memorable title and the area was obtainable.

The intention: Bun will turn out to be a drop-in alternative for Node.js, Deno, serverless JavaScript, and instruments corresponding to webpack, Babel, and Yarn. Moderately than working npm begin to launch your Node script, you’ll be able to run bun begin and make the most of Bun’s velocity.

Tasty Bun Advantages

Node.js and Deno use Chrome’s V8 JavaScript engine. Bun opts for the JavaScriptCore engine which powers WebKit browsers corresponding to Safari. Bun itself is written in Zig — a low-level programming language with guide reminiscence administration and native threading to deal with concurrency. The result’s a light-weight runtime with a smaller reminiscence footprint, faster start-up occasions, and efficiency which could be 4 occasions sooner than Node.js and Deno below sure (benchmarking) situations.

Like Deno, Bun has native assist for each JavaScript and TypeScript with out requiring a third-party transpiler or configuration. It additionally helps .jsx and .tsx information to transform HTML-like markup to native JavaScript. Experimental assist for working WebAssembly-compiled .wasm information is out there.

Internally, Bun makes use of ES Modules, helps top-level await, interprets CommonJS, and implements Node’s node_modules decision algorithm. Bun caches modules in ~/.bun/set up/cache/ and makes use of hardlinks to copy them right into a undertaking’s node_modules listing. All initiatives in your system will due to this fact reference a single occasion of the identical library, which reduces diskspace necessities and improves set up efficiency. (Notice that macOS installations retain native variations for velocity.)

Bun helps Node’s package deal.json, npm equal instructions, and bunx — a npx-like choice to auto-install and run packages in a single command. For instance:

bunx cowsay "Howdy, world!"

bun init scaffolds empty initiatives in the identical method as npm init, however it’s also possible to template a brand new undertaking with bun create <template> <vacation spot>, the place <template> is an official package deal, a Github repository, or a neighborhood package deal. For instance, to create a brand new Subsequent.js undertaking:

bun create subsequent ./myapp

Bun features a bundler to import all dependencies right into a single file and might goal Bun, Node.js, and client-side JavaScript. This reduces the necessity to use instruments corresponding to esbuild or Rollup:

bun construct ./index.ts —outdir ./out

Most command-line interface choices can be found by way of a JavaScript API, so it’s doable to create refined construct scripts with out a devoted activity runner. Right here’s an equivalent construct to the command above:

await Bun.construct({
  entrypoints: ['./index.ts'],
  outdir: './out',

Bun has an ordinary take a look at runner like Deno and Node.js 20. Operating bun take a look at executes scripts named like this:

*.take a look at.jsx

There’s no want for nodemon-like instruments, since bun has a —watch flag which restarts scripts or assessments while you modify a dependency file. Restarts are so quick that it turns into doable to live-reload on every keystroke. (Whether or not that is sensible and never a distraction is one other matter!)

Stay reloading isn’t fairly! (Warning: flickering content material!) View unique animated GIF.

The same —scorching mode is out there, the place Bun watches for modifications and comfortable reloads modules. All information are re-evaluated, however the world state persists.

Setting variables contained in undertaking .env information are mechanically loaded and parsed, making them obtainable in Bun functions, so there’s no want to make use of packages corresponding to dotenv.

In addition to its personal Bun APIs for networking, file entry, baby processes, and so forth, Bun helps:

  • Internet APIs corresponding to fetch, URL, blob, WebSocket, JSON, setTimeout, and occasions.

  • Node.js compatibility APIs corresponding to console, assert, dns, http, path, stream, and util, in addition to globals together with __dirname, and __filename. Bun claims that 90% of the most-used APIs are absolutely carried out, though it’s best to double-check these particular to your undertaking.

Lastly, Bun has a local SQLite3 shopper — bun:sqlite — which might cut back the variety of dependencies required in some initiatives.

Underbaked Bun

Bun is in lively growth, so the next options are but to look:

  • a Deno-like permission mannequin to limit entry to information, the community, baby processes, atmosphere variables, OS info, and so forth. Including permission rights later may cause issues (as seen in Node.js 20), so I think choices will arrive earlier than the model 1.0 launch.

  • Instruments corresponding to a Learn-Eval-Print Loop (REPL), dependency inspector, linter, debugger, code formatter, documentation generator, and a standalone script generator are lacking however ought to seem over time.

Putting in Bun

Bun has not reached a model 1.0 launch, but it surely’s obtainable as a single binary you’ll be able to set up on Linux, macOS, and Home windows WSL with:

curl -fsSL up | bash

Alternatively, you’ll be able to set up it with Node’s package deal supervisor:

npm set up -g bun

A local Home windows model is coming, though the Home windows Subsystem for Linux is commonly the better and better-performing choice. Alternatively, it’s also possible to use Docker to run Bun in a container:

docker run —rm —init —ulimit memlock=-1:-1 oven/bun

As soon as put in, you’ll be able to improve the engine with:

bun improve

To uninstall, take away the ~/.bun binary and cache listing:

rm -rf ~/.bun

Then replace your shell configuration file (.bashrc, .zshrc, or related) to take away ~/.bun/bin references from the $PATH variable.

Utilizing Bun

Bun is dependable in the event you use it from the beginning of your undertaking. Pace is best than Node.js, though you’re unlikely to see a major efficiency enhance until your app is doing particular intensive duties such heavy SQLite processing or WebSocket messaging.

Node.js compatibility is sweet for smaller, easier initiatives, and I efficiently launched some scripts utilizing bun begin with out making modifications. Extra advanced functions did fail, with obscure error messages generated deep within the node_modules hierarchy.

Bun vs Deno vs Node.js

Deno addressed a lot of Node’s drawbacks, however builders didn’t essentially really feel compelled to modify:

  1. Deno didn’t assist Node’s third-party modules.
  2. Migrating from Node.js to Deno required studying new methods.
  3. Whereas Deno supplied a greater growth expertise, Node.js was adequate.

Deno has now added Node.js compatibility choices. That was the simplest solution to get builders to transition to Deno, however within the meantime, Node.js has adopted a few of Deno’s options, together with ES modules, a local take a look at runner, and a —watch mode.

Bun has taken a special method, aiming to be a quick, Node-compatible engine with Deno’s developments. The indicators are promising, but it surely’s not there but:

  • Efficiency is nice, however few builders complain about Node.js velocity.

  • Compatibility is sweet, however it will likely be a problem to assist all Node.js modules in a special JavaScript engine. Can JavaScriptCore sustain with V8 developments with far much less funding?

  • Bun has the potential to switch your tooling suite, but it surely’s but to supply the total vary present in Deno.

Abstract: Ought to You Swap to Bun?

Bun is an completed JavaScript runtime, however Node.js stays the champion for mission-critical initiatives or legacy functions. It is best to attempt working your app utilizing bun begin, however the bigger your codebase, the much less probability it should execute with out modification.

Deno might be a greater choice than Bun for brand spanking new initiatives, provided that it’s extra mature and feature-complete.

Bun is nice, but it surely’s new, being actively developed, and but to succeed in a model 1.0 milestone. The runtime is steady, however few would guess on its long-term future at this stage. That stated, Bun has some fascinating concepts which I hope each the Node.js and Deno groups take into account adopting (CLI APIs and auto-loaded .env please!)

On a aspect notice, I like Bun’s title, however it may be tough to seek for sources. ChatGPT makes the daring assertion that “There is no such thing as a extensively recognized JavaScript runtime known as ‘Bun’. So far as I’m conscious, there is no such thing as a such know-how within the JavaScript ecosystem.” This can be as a result of post-2021 information is proscribed, though sure questions return a Bun response and an apology for the error!

I think we’re heading towards an age of isomorphic server-side JavaScript, the place module builders try to put in writing code that’s suitable with all runtimes: Node.js, Deno, Bun, serverless, edge, embedded, and so on. We might finally attain some extent the place JavaScript runtimes are principally interchangeable in the identical method browsers are immediately.

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