Bun v0.6.7

Jarred Sumner · June 2, 2023

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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().

Now we're releasing bugfixes to Node.js compatibilty that enable Discord.js, Prisma, and Puppeteer to run in Bun. We've also fixed a regression with bun build --compile, a regression from native CommonJS support that could cause a crash, and several bundler bugfixes.

To install Bun:

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

To upgrade Bun:

bun upgrade

Use Prisma in Bun

Prisma is a popular ORM for Node.js, and it now works in Bun!

import { PrismaClient } from "@prisma/client";

const prisma = new PrismaClient();

const user = await prisma.user.create({
  data: {
    name: "Alice",
    email: "alice@prisma.io",


This was a popular feature request in Bun.

Why didn't Prisma work before?

There were several Node-API bugs that prevented Prisma from working in Bun. @cirospaciari fixed those bugs in Bun v0.6.7 (this release).

There was also a transpiler bug that was fixed in Bun v0.6.5 (two releases ago).

Several Node.js compatibility bugfixes led to resolving the issues blocking Prisma from working.

Use Discord.js in Bun

Discord.js is the most popular library for building Discord bots. It now works in Bun, thanks to @paperdave.

import { Client, IntentsBitField } from "discord.js";

const client = new Client({
  intents: [

client.on("ready", () => {
  console.log(`Logged in as ${client.user.tag}!`);

client.on("messageCreate", (msg) => {
  if (msg.content === "ping") {


This also was a popular feature request in Bun.

Why didn't Discord.js work before?

Node.js compatibility bugs in node:http and undici in Bun, mostly. There was a couple WebSocket bugs too. @paperdave fixed those bugs in Bun v0.6.7 (this release).

We didn't make any Discord.js-specific changes to Bun's code, just Node.js compatibility bugfixes that resolved the issues blocking Discord.js from working.

Use Puppeteer in Bun

Puppeteer is a popular library for automating Chromium. It now works in Bun, thanks to @cirospaciari.

import puppeteer from "puppeteer";

const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.goto("https://elysiajs.com");
await page.screenshot({ path: "example.png" });
await browser.close();

Why didn't Puppeteer work before?

Issues with node:net and CommonJS <> ES Module interop, mostly.

Faster node:crypto hashing

@paperdave landed performance improvements to EventEmitter and node:crypto that leads to about 2x faster hashing on small inputs in Bun.


We originally intended to land these changes around Bun v0.5.0 but the tests were failing on CI. We finally got around to fixing it and landing the changes. Thanks @paperdave!

Better error message for CommonJS files

Bug fixes

Regressions from the CommonJS rewrite that have been fixed:

  • A crash that could occur when many CommonJS files were loaded at once due to incorrectly managing the lifetime of the scope extension
  • Bun was sometimes injecting import.meta.resolveSync into CommonJS files, which broke some packages like @prisma/client
  • Bun was not inserting __dirname or __filename correctly in the CommonJS module wrapper

Hopefully there won't be many more of those.

Two significant differences remain for CommonJS in Bun versus Node.js:

  • Module evaluation order. CommonJS files in Bun are evaluated at the time ES modules are parsed. We will see if that ends up breaking things. If it does, we will align it with Node.js' behavior.
  • More named exports are available. Node.js relies on static analysis to determine named exports of CommonJS files. Bun uses runtime checks that should expose more named exports. This is a feature, as it means more named imports will work in Bun. But, it is a difference and differences can potentially break things. We'll keep an eye on this.

Bundler & transpiler bugfixes

  • Certain modules were incorrectly adding __esModule to their exports which broke bundling Express apps. Thanks to @dylan-conway for fixing.
  • Bun was incorrectly choosing jsxDEV over jsx when transpiling JSX when specified in a tsconfig.json or jsconfig.json file. Thanks to @dylan-conway for fixing.
  • bun build --compile was broken in 0.6.5, it now works again and our CI will catch this in the future. Thanks to @dylan-conway for fixing.
  • In certain cases, Bun would incorrectly double-escape UTF-8 string literals with $ inside backtick quotes, which broke packages like typemorph
  • For JSON files, default imports were incorrectly returning an empty object. Thanks to @dylan-conway for fixing.

More features

Bun now supports the NO_COLOR environment variable, which disables colored output in the CLI. Thanks to @electroid for adding.

Internal changes

Bun's builtin ES modules are now bundled & minified with Bun, thanks to @paperdave