Bun

Bun v1.2.4

Jarred Sumner · February 26, 2025

This release makes Bun.build up to 60% faster on macOS, introduces codesigning support for single-file executables on macOS, improves dev server stability, fixes a regression from v1.2.3 affecting Hono, fixes a regression from v1.2.3 affecting bun init on Windows, fixes a bug where stdin streams that were paused immediately would prevent the process from exiting, fixes a bug where Buffer.prototype.indexOf could return incorrect results when searching for number values with a byte offset, and fixes a bug where net.Socket error handlers could receive JSC::Exception objects instead of Error instances.

To install Bun

curl
npm
powershell
scoop
brew
docker
curl
curl -fsSL https://bun.sh/install | bash
npm
npm install -g bun
powershell
powershell -c "irm bun.sh/install.ps1|iex"
scoop
scoop install 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

Bun.build gets up to 60% faster on macOS

Bun now uses a dedicated I/O threadpool for file operations during builds on macOS and Windows, significantly improving build performance. This addresses filesystem contention issues that were slowing down builds on these platforms.

This optimization is automatically enabled on macOS and Windows systems with more than 3 logical CPUs, where it provides the most benefit.

Codesign single-file executables on macOS

Previously, the executables produced for macOS by bun build --compile could not be code signed, due to an issue with our code handling the Mach-O executable format. Now, these executables can be code signed.

Learn how to codesign compiled executables on macOS.

Fixed: bun init ↑↓ on Windows

The bun init command now works properly on Windows with full support for keyboard navigation. Arrow keys (up/down) work correctly for navigating options, Enter works for selection, and Ctrl+C works to cancel the operation.

PS C:\Users\bun\project> bun init

? Select a project template - Press return to submit.
    Blank
    React
❯   Library

Thanks to @pfgithub for the contribution!

Fixed: Regression from v1.2.3 affecting Hono

When using Hono with Bun, some applications that export default a Hono instance would fail to start with an argument validation error for routes in Bun.serve due to a name conflict with the routes option in Hono. We've added a workaround and integration tests to avoid introducing regressions that affect Hono in the future.

import { Hono } from "hono";

const app = new Hono();

app.get("/", (c) => c.text("Hello World!"));

export default app; // Now works properly with Bun.serve

Node.js compatibility

Fixed: Stat assertion failure on Windows

We fixed a bug that in certain cases caused an assertion failure when calling stat in node:fs on Windows.

import { stat } from "node:fs/promises";

const stats = await stat("large-file.txt");
console.log(stats.size, stats.mtime);

Fixed: net.Socket error handling

A bug has been fixed in node:net socket error handling where bare JSC::Exception objects could be passed to JavaScript code. JSC::Exception is a class used internally by the JavaScript engine, and these objects exhibit strange behavior if they are passed to JavaScript code. Now, all exception objects are properly converted to JavaScript Error instances before being passed to error handlers.

const socket = new net.Socket();
socket.on("error", (err) => {
  console.log(err instanceof Error); // Now always true
});

Thanks to @heimskr for fixing this!

net.SocketAddress

Bun now exposes the SocketAddress class matching Node.js' API, providing a way to represent and manipulate IP socket addresses.

import { SocketAddress } from "node:net";
const addr = SocketAddress.parse("[0::1]:1234");
// ipv6 ::1 1234
console.log(addr.family, addr.address, addr.port);

Thanks to @DonIsaac for the contribution!

Buffer fixes

Fixed: Buffer.prototype.indexOf for number values with byteOffset

While improving our Node.js test coverage for Buffer, we introduced a bug in Bun v1.2.3 that affected Buffer.prototype.indexOf when searching for number values with a byte offset. This has been fixed to properly handle number searches by considering the byte offset, matching Node.js behavior. We've also submitted a PR to Node.js to improve their test coverage for this case (and ours by using their tests).

const buffer = Buffer.from("abcdef");

// Searching for character codes (numbers) now works correctly
buffer.indexOf(100, 2); // Returns 3 (byte value 100 = 'd' found at index 3)
buffer.indexOf(102, 5); // Returns 5 (byte value 102 = 'f' found at index 5)
buffer.indexOf(102, -1); // Returns 5 (negative offset searches from the end)
buffer.indexOf(102, 6); // Returns -1 (searching past the end of buffer)

Thanks to @nektro for the fix!

Fixed: process.argv in --print and --eval modes

The bun --print and bun --eval commands (or -p and -e) no longer include [eval] in the process.argv array. Previously, this was included between the path to the Bun executable and the actual command-line arguments in place of the name of the JavaScript file being run. Now, there is no extra argument in this position which matches Node.js's behavior.

// Previously
$ bun --print "process.argv" arg1 arg2
["/path/to/bun", "/your/cwd/[eval]", "arg2"]

// Now (matching Node.js)
$ bun --print "process.argv" arg1 arg2
["/path/to/bun", "arg1", "arg2"]

Thanks to @RiskyMH for the contribution!

Fixed: hang when calling pause() on process.stdin

We fixed a bug where stdin streams that were paused immediately would prevent the process from exiting. This affected readline and other packages.

process.stdin.on("data", () => {});
process.stdin.pause();
// previously: the process would never exit
// now: the process exits

Thanks to @pfgithub for the fix!

Other improvements

Fixed: Binary data types in PostgreSQL

Bun's PostgreSQL client now correctly handles binary data types and custom type OIDs. This resolves issues with binary format detection and custom data types when using the SQL API.

// Binary data and custom types are now properly handled
const result = await sql`SELECT bytea_column, custom_type_column FROM my_table`;

Thanks to @cirospaciari for the contribution!

Faster array.includes

WebKit rewrote Array.prototype.includes in native C++ code, and this makes Array.prototype.includes 1.2 to 2.8 times faster in microbenchmarks.

This rewrite allows DFG and FTL (JavaScriptCore's optimizing JIT compilers, which convert JavaScript into native machine code to execute it as fast as possible) to leverage the fast native implementation (similar to Array.prototype.indexOf).

Thanks to @sosukesuzuki for this contribution!

Dev server stability improvements

This release contains several stability improvements for Bun's new development server introduced in 1.2.3. We're excited to keep improving the development experience with Bun in future releases.

Thanks to @paperclover for the fixes!

define support in bunfig.toml for static files

You can now set the define option in the [serve.static] section of bunfig.toml to inline constants into static files. This works the same way as the existing runtime option. Unlike environment variables, defines support arbitrary JSON, not just strings.

bunfig.toml
index.html
index.ts
bunfig.toml
[serve.static]
# outer quotes for TOML, inner quotes for JavaScript
define = { CONFIG = "{ \"version\": \"1.0\", \"beta\": false }" }
index.html
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8" />
    <title>Bun</title>
  </head>
  <body>
    <script src="index.ts"></script>
  </body>
</html>
index.ts
// Logs "Hello from app 1.0"
console.log("Hello from app " + CONFIG.version);
if (CONFIG.beta) {
  console.log("enable beta features!");
}

$ bun index.html
 DEV  Bun v1.2.4 ready in 6.66 ms

➜ http://localhost:3000/

Press h + Enter to show shortcuts
Bundled page in 1ms: index.html

Thanks to @paperclover for adding this feature!

Improved accessibility in bun init templates

The React templates created by bun init now respect the prefers-reduced-motion media query by disabling all animations when enabled. This improves accessibility for users who are sensitive to motion or have vestibular disorders.

@media (prefers-reduced-motion) {
  *,
  ::before,
  ::after {
    animation: none !important;
  }
}

Thanks to @jakeboone02 for the contribution!

bun pm pack --filename

We've added support for the --filename flag in bun pm pack, allowing you to specify the name of the output tarball. The value is relative to the project root and can include subdirectories.

# output to ./lodash-4.tgz
bun pm pack --filename lodash-4.tgz

# output to ./build/lodash-4.tgz
bun pm pack --filename build/lodash-4.tgz

Thanks to @versecafe for implementing this!

Updated SQLite to 3.49.1

Bun now includes SQLite 3.49.1, bringing the latest improvements and bug fixes from the SQLite project to Bun's built-in SQLite implementation.

import { Database } from "bun:sqlite";

const db = new Database(":memory:");
console.log(db.prepare("SELECT sqlite_version()").get());
// { "sqlite_version()": "3.49.1" }

You can read the SQLite 3.49.1 release notes for more information on the changes. On macOS, Bun continues to use the system-provided SQLite by default, which generally improves performance.

Bug fixes

Fixed: Error handling for invalid JSON imports

Bun v1.2.3 regressed error handling for invalid JSON imports.

// This now produces a proper error
import data from "./invalid.json";
// Or with require()
const data = require("./invalid.json");

We've improved test coverage for JSON imports and added a fix to properly handle invalid JSON files.

Thanks to @dylan-conway for the contribution!

Fixed: Glob pattern parsing for nested braces

The glob pattern matcher in Bun now correctly handles nested braces in pattern expressions. This fixes an issue where patterns with nested brace expressions like {a,{d,e}b}/c would not match correctly.

// Previously didn't work correctly
const glob = new Glob("{a,{d,e}b}/c");
// Now correctly matches
expect(glob.match("a/c")).toBeTrue();

Thanks to @shulaoda for the contribution!

Thanks to 17 contributors!

Bun v1.2.3