Bun v0.0.44

To upgrade:

bun upgrade

Next.js 12

Bun works with Next.js 12 now. Before, it only supported 11.1.2. This includes support for React 18 (react@alpha). React Server Components is not supported yet, but it will be. I promise :)

Other stuff

• (bun run) ZSH completions should auto-install correctly now. This will automatically apply when you run bun upgrade
• (bun dev) Fixed a mistranspilation when using require from app code to a bundled module (e.g. require("relay-devtools"))
• (bun bun) Fixed an issue with symlinked workspace packages when using alwaysBundle that prevented them from being correctly imported if enough levels of indirection were added
• Fixed undefined behavior when invalid UTF-8 codepoints were inside source code text printed in an error message
• (bun-macro-relay) Worked around a bug that could cause it to not correctly import graphql depending on the environment
• (bun create) bumped the hardcoded Next.js version set to 12.0.2
• Bun.js: rename Bun.sleep -> Bun.sleepSync

Full Changelog: Jarred-Sumner/bun@bun-v0.0.42...bun-v0.0.44

Bun v0.0.42

To upgrade:

bun upgrade

tab completions for bun run

bun run now has tab completions for zsh and fish that show scripts from package.json and bins from node_modules/.bin.

Install:

bun upgrade
bun completions 

Going forward, bun upgrade also updates completions, so you shouldn't have to do that again.

Bun.js

Bun now has a builtin "supports-color" polyfill, the package used by chalk to detect ANSI color support.

The TypeScript in this screenshot runs 2x faster in Bun.js than in Node.js:

Other stuff:

• node-fetch & isomorphic-fetch polyfills work now. When an npm package imports node-fetch, Bun.js will automatically replace it with Bun's native implementation.
• Bun.sleep(ms) lets you synchronously sleep. No promises
• Fixed an edgecase with the CommonJS transform that affected export default (thank you @evanwashere for flagging)
• Several more encoding issues specific to the JavaScriptCore integration were found & fixed, though there are a couple more I still need to fix.

JavaScript Lexer

• Fixed a regression with \0 (and added an integration test)

Misc

• --version now prints a newline at the end
• -v is now shorthand for --version
• Fixed spacing with the CLI help menu (thanks @KishanBagaria for flagging)
• -u is now shorthand for --origin. Might rename that to --url in a future release.

Bun v0.0.41

To upgrade:

bun upgrade

What's new:

bun run:

bun run ./file.js now supports running JavaScript, TS, TSX, and JSX files using Bun.js. If you pass bun run a filepath to a .js, .jsx, .tsx, or .ts file, it will run it with Bun.js instead of saying "error: Missing script". This is very experimental!

Bun.js

^{Bun.js is Bun's JavaScript runtime environment.}

• Top-level await works now
• performance.now() is implemented

Bug fixes

• [.env loader] functions from bash were exported incorrectly due to parsing process environment variables similarly to .env files which is unnecessary. Now process environment variables are passed through without extra parsing
• fetch() wasn't working due to a silly mistake. That's fixed

Bun v0.0.40

It's been a busy couple weeks.

Important: the bun-cli npm package is deprecated. It will not receive updates.

Please upgrade Bun by running:

# Remove the npm version of bun
npm uninstall -g bun-cli

# Install the new version
curl https://bun.sh/install | bash

For future upgrades:

bun upgrade

Now the fun part.

bun run

~35x faster package.json "scripts" runner, powered by Bun. Instead of npm run, try bun run.

Like npm run, bun run reads "scripts" in your package.json and runs the script in a shell with the same PATH changes as npm clients. Unlike npm clients, it's fast.

You can use bun run in projects that aren't using Bun for transpiling or bundling. It only needs a package.json file.

When scripts launch a Node.js process, bun run still beats npm run by 2x:

Why? Because npm clients launch an extra instance of Node.js. With npm run, you wait for Node.js to boot twice. With bun run, you wait once.

For maximum performance, if nested "scripts" run other npm tasks, bun run automatically runs the task with Bun instead. This means adding many tasks won't slow you down as much.

bun run supports lifecycle hooks you expect like pre and post and works when the package.json file is in a parent directory.

Two extra things:

• bun run also adds any node_modules/.bin executables to the PATH, so e.g. if you're using Relay, you can do bun run relay-compiler and it will run the version of relay-compiler for the specific project.
• bun run has builtin support for .env. It reads: .env.local, then .env.development || .env.production (respecting your NODE_ENV), and .env in the current directory or enclosing package.json's directory

Oh and you can drop the run:

Reliability

Lots of work went into improving the reliability of Bun over the last couple weeks.

Here's what I did:

• Rewrote Bun's filesystem router for determinism and to support catch-all + optional-catch-all routes. This is an oversimplification, but the routes are sorted now
• Improved testing coverage. Bun now has integration tests that check a simple Next.js app bundles & server-side prerenders successfully. If JavaScriptCore's JIT is not enabled while server-side rendering, the tests fail. Another integration test checks that a simple Create React App loads. It uses bun create to bootstrap the projects.
• Fix all known unicode encoding & decoding bugs. Part of what makes parsing & printing JavaScript complicated is that JavaScript officially uses UTF-16 for strings, but the rest of the files on your computer likely use UTF-8. This gets extra complicated with server-side rendering because JavaScriptCore expects either a UTF-16 string for source code or a UTF-8 string. UTF-16 strings use about twice as much memory as UTF-8 strings. Instead of wasting memory, Bun escapes the strings where necessary (but only for server-side rendering)
• Fixed several edgecases with the .env loader. .env values are now parsed as strings instead of something JSON-like

There's still a lot of work ahead, but Bun is getting better.

Sometimes, speed and reliability is a tradeoff. This time, it's not. Bun seems to be about 3% faster overall compared to the last version (v0.0.36). Why? Mostly due to many small changes to the lexer. Inlining iterators is good.

Bun v0.0.36

bun create

bun create is a new subcommand that lets you quickly create a project from a template.

To create a new React project (based on Create React App)

bun create react ./app

11x faster than yarn create react app on my Macbook Pro (both installing dependencies via yarn)

To create a new Next.js project (based on Create Next App)

bun create next ./app

To create from a GitHub repository:

bun create jarred-sumner/calculator calc

To see a list of templates:

bun create

Right now, there are only two "official" templates (and they're mostly empty) – but you can add more. bun create fetches from packages published in the examples folder of Bun's GitHub repo. PRs are very welcome!

Local templates

Many developers have boilerplate code copied for new projects.

That's why bun create also searches $HOME/.bun-create for local templates.

Add a folder with a package.json in $HOME/.bun-create/my-local-template and then you can run:

bun create my-local-template ./foo

This copies the contents of my-local-template, initializes a git repository, runs any preinstall steps, installs dependencies (if any exist), runs any postinstall steps and rewrites the name field in package.json to foo.

It uses the fastest system calls available for copying files. bun create copies files faster than cp. Here is a stupid microbenchmark

Performance

The slowest part is running your NPM client to install node_modules. The second slowest part is downloading the tarball from GitHub (or NPM if it's from Bun's examples folder). Third is git.

Other stuff

• fetch now supports gzip
• https support in fetch was completely rewritten to be more reliable. TLS is now powered by s2n-tls
• fetch now supports Transfer-Encoding: chunked. It didn't before, which was embarrassing.
• Set self to globalThis in Bun.js. This improves compatibility with some npm packages
• There are two new test binaries in misctools/, tgz and fetch. tgz is like gunzip except harder to use and fetch is sort of like curl? These are really just to help me test some things in isolation from the rest of Bun

Bun v0.0.34

Features

Slightly better tsconfig.json handling:

• jsxImportSource support – if you set jsxImportSource to "@emotion/react", JSX will auto-import from "@emotion/react/jsx-dev-runtime" instead of "react/jsx-dev-runtime"
• jsxFragmentFactory support – this lets you override what <> transforms into. By default it's "Fragment", since <> becomes React.Fragment normally.
• jsxFactory support – if you set jsxFactory to "h", when using the classic JSX runtime, it will run h instead of createElement

This makes it easier to use @emotion/react, preact, and other JSX runtimes with Bun.

Bug fixes

• [fetch] Fix bug with HTTP request bodies for http (not https) requests
• Fix JSX transform edgecase with static children to match Babel's behavior (static === children.length > 1)
• Fix node_module resolver edgecase when resolving from the dev server (not bun bun) that happened when resolving workspace packages above the project root that expect dependencies from the project. This applied to pnpm

Other:

• Add a small end-to-end test for emotion JSX
• Add a small end-to-end test for React Context.Provider & Context.Consumer
• Add analytics

Bun v0.0.32

Bug fixes

• [Linux] Fix Bun failing to start when the system-installed version of ICU didn't match the dynamically linked version. The fix here is to statically link ICU. This unfortunately doubles the binary size of Bun on Linux
• Fix running bun bun on a networked filesystem. This is particularly relevant to WSL. The normal posix C function for moving files doesn't work if the source file is on a different mounted filesystem than the target. This fix detects the error and attempts to use sendfile() so that it copies the file faster than it would by reading the memory manually.

Bun v0.0.29

5% end-to-end performance improvement by reducing allocations for Identifiers in the JavaScript/TypeScript parser.

Also, bun-cli wasn't installing on Linux correctly. Now it is!

Bun v0.0.28

Bun on Linux x64

Bun is now available for Linux x64. That includes a filesystem watcher leveraging inotify, Linux's API for watching files as well as macros and SSR/SSG.

When bundling 20 copies of Three.js on Linux x64, Bun performed:

• 1.6x faster than esbuild
• 13.5x faster than Parcel 2
• 19.5x faster than Webpack (without babel-loader)

I have done very little work on optimizing Bun for Linux. I'm not satisfied with these numbers, but it's a start.

^{Bun uses the GOMAXPROCS to control concurrency despite not being written in Go because I didn't want to think about what to name the variable}

The runs with GOMAXPROCS=1 are single-threaded runs.

Bun single-threaded performed 2.2x faster than esbuild single-threaded. The relative gap between single-threaded and concurrent performance implies there's room for improvement in Bun's concurrency code. This machine has 6 cores (nproc returns 12) and 64 GB of memory.

Other

• Bun's installed binary is now about 28% smaller

Bun v0.0.27

Features

Relay GraphQL client

You can now use Facebook's Relay GraphQL framework with Bun via bun-macro-relay.

bun-macro-relay implements the Bun equivalent of babel-plugin-relay.

Input:

const query = graphql`
  query Bacon {
  }
`;

Output:

import Bacon from '__generated__/Bacon.graphql';
const query = Bacon;

This macro is implemented entirely in TypeScript - not in native code. For install instructions, head over to bun-macro-relay.

Automatically remap macros

// Instead of having to change every import like this:
import { css } from "@emotion/react";

// To this:
import { css } from "macro:bun-macro-emotion-react";

// Now you don't have to change your code
import { css } from "@emotion/react";

^{note: @emotion/react is not implemented yet!}

To use this, add this to your package.json (and remove the comments):

  "bun": {
    "macros": {
      // "react-relay" is the import path to rewrite
      "react-relay": {
       // rewrite the "graphql" import to instead point to "bun-macro-relay/bun-macro-relay.tsx"
        "graphql": "bun-macro-relay/bun-macro-relay.tsx"
      }
    }
  },

Remapping this way only applies to macros. To rewrite imports otherwise, Bun will read paths from tsconfig.json or jsconfig.json.

Bug fixes

• Fix edgecase with cjs -> esm interop runtime code when the ESM export was marked as not extensible
• Fix potential infinite loop on calling macros
• Fix incorrect jsxDEV transform when source feature flag is off and a runtime error occurs in a component being rendered
• Fix dead-code elimination edgecase with call expressions
• Fix edgecase with parsing .env containing very short strings

More macro features

• <import> lets you inject an import statement into a module. It accepts default, which is the default import alias and you can pass a namespace object where the object maps the import names to their names in the current file
• <id> lets you reference an import (and eventually, other symbols too)
• <inject> will insert each child element to the module scope. This currently only works with <import>, but it will work with other statements eventually.

Here's an example:

  const importStmt = (
    <import default="MyImportName" path="foo/bar" />
  );

  return (
    <>
      <inject>{importStmt}</inject>
      <id to={importStmt.namespace.MyImportName} />
    </>
  );