Bun

Bun v0.6.14

Ashcon Partovi · July 12, 2023

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As a reminder: Bun is an incredibly fast JavaScript runtime, bundler, transpiler, and package manager — all in one.

We've been releasing a lot of changes to Bun recently, here's a recap in case you missed it:

  • v0.6.0 - Introducing bun build, Bun's new JavaScript bundler.
  • v0.6.2 - Performance boosts: 20% faster JSON.parse, up to 2x faster Proxy and arguments.
  • v0.6.3 - Implemented node:vm, lots of fixes to node:http and node:tls.
  • v0.6.4 - Implemented require.cache, process.env.TZ, and 80% faster bun test.
  • v0.6.5 - Native support for CommonJS modules (previously, Bun did CJS to ESM transpilation),
  • v0.6.6 - bun test improvements, including Github Actions support, test.only(), test.if(), describe.skip(), and 15+ more expect() matchers; also streaming file uploads using fetch().
  • v0.6.7 - Node.js compatibility improvements to unblock Discord.js, Prisma, and Puppeteer
  • v0.6.8 - Introduced Bun.password, mocking in bun test, and toMatchObject()
  • v0.6.9 - Less memory usage and support for non-ascii filenames
  • v0.6.10 - fs.watch(), bun install bug fixes, bun test features, and improved CommonJS support
  • v0.6.11 - Addressed a release build issue from v0.6.10.
  • v0.6.12 - Sourcemap support in Error.stack, Bun.file().exists(), and Node.js bug fixes.
  • v0.6.13 - Implemented mock Date, faster base64 encoding, and fixes for WebSocket and node:tls.

To install Bun:

curl
npm
brew
docker
curl
curl -fsSL https://bun.sh/install | bash
npm
npm install -g bun
brew
brew tap oven-sh/bun
brew install bun
docker
docker pull oven/bun
docker run --rm --init --ulimit memlock=-1:-1 oven/bun

To upgrade Bun:

bun upgrade

Better support for process

Bun has improved support for the Node.js process object.

Memory usage

You can now use process.memoryUsage() to get the memory usage of Bun's process.

console.log(process.memoryUsage());
// {
//  rss: 4935680,
//  heapTotal: 1826816,
//  heapUsed: 650472,
//  external: 49879,
//  arrayBuffers: 9386
// }

CPU usage

You can also get the current CPU usage from Bun using process.cpuUsage().

console.log(process.cpuUsage());
// {
//  user: 38579,
//  system: 6986
// }

Signal events

You can now use process.on() to listen and run code when the process receives a signal event.

process.on("SIGINT", () => {
  console.log("Interrupt from keyboard");
});

Exit events

If you don't know which signal to listen for, you can also listen for a generic exit or beforeExit event.

process.on("beforeExit", (code) => {
  console.log("Event loop is empty and no work is left to schedule.", code);
});

process.on("exit", (code) => {
  console.log("Exiting with code:", code);
});

process.kill

You can now use process.kill(pid, signal), which kills a process by pid.

process.kill(123, "SIGTERM");

getuid, geteuid, getgid, getegid, getgroups

The following methods have been added:

  • process.getegid()
  • process.geteuid()
  • process.getgid()
  • process.getgroups()
  • process.getuid()

process.assert

process.assert() is a deprecated alternative to require("assert"). Bun adds this deprecated function for compatibility with existing npm packages.

process.assert(false, "PleAsE don't Use THIs It IS dEpReCATED");

process.reallyExit

process.reallyExit() is used by some npm packages to exit without triggering the "exit" event handler. This is an undocumented function which Bun now implements for ecosystem compatibility reasons.

process.reallyExit(); // probably just use process.exit() though

Class constructors in console.log

Previously, when a value was printed to console.log, a class would was mis-categorized as a function. This has now been fixed and shows that the value is a class.

console.log(class A {});
// Previous: [Function: A]
// Now: [class A]

Fixed TypeScript decorator bug

Previously, Bun had a bug where decorators were not evaluated when used on an anonymous default export. This has been fixed.

function decorator(target: unknown, propertyKey: unknown) {
  // ...
}

export default class {
  @decorator
  method() {
    // ...
  }
}

Fixed fetch in URLs without slash

Previously, Bun would throw an error when a URL used in fetch() did not have a slash. This has been fixed.

await fetch("http://example.com?a=b");
// Previous: <throw>
// Now: Response { ... }

Fixed 2 crashes in Error.captureStackTrace

We've added a small stress test for Error.captureStackTrace and that led to fixing two crashes:

  • When the sourceURL of a stack frame was empty and Error.captureStackTrace() was called, incorrectly initialized memory could sometimes be passed to the stack trace sourcemapper. This has been fixed.
  • Creating the array of CallSite objects could sometimes cause a crash due to creating an Array using the fast path which prohbits additional GC-owned memory allocations until the Array has been fully initialized. Since the CallSite objects are each a GC-owned allocation, this could cause a crash when GC happens while creating these (suhc as when called repeatedly in a loop). This has been fixed.

Implemented throwIfNoEntry

Implemented support for the throwIfNoEntry option for stat and lstat in node:fs. If set to false and the file does not exist, it will return undefined instead of throwing an error.

import { statSync } from "node:fs";

statSync("./does-not-exist.txt"); // <throws>
statSync("./does-not-exist.txt", { throwIfNoEntry: false }); // undefined

Other changes

  • Implemented getCurves() in node:crypto

  • Added support for obscure HTTP methods.

  • Fixed a bug that caused bun build to non-deterministically rename symbols.

  • Fixed an off-by-one error that could cause stack traces show the wrong preview.

  • Fixed a bug where the readable event was being emitted after a stream was destroyed.

  • Fixed a bug where digest("binary") was not implemented properly.

  • Fixed bad coercion from large numbers and BigInt in node:fs.

  • Fixed the connection event from being emitted when it shouldn't.

  • Fixed a bug in HTMLRewriter where element.attributes used the wrong encoding.

  • Fixed a bug where the JIT from Buffer.isBuffer() would become invalid.

  • Fixed a regression for React support where the bundle size was larger than in previous releases.

  • Fixed a bug where ref() and unref() did not return the Timer object.

  • Fixed a bug where the metadata bits from randomUUID() were incorrect.

  • Fixed a crash from invalid utf-8 data in node:string_decoder.

  • Fixed a bug where Set-Cookie was not present in express-session because of a monkey-patch. (Thanks to @Hanaasagi for fixing those last three bugs!)

Changelog

See the changelog on GitHub