Intro

What is Bun?

Installation

Quickstart

TypeScript

Templating

bun init

bun create

Runtime

bun run

File types

TypeScript

JSX

Environment variables

Bun APIs

Web APIs

Node.js compatibility

Single-file executable

Plugins

Watch mode

Module resolution

Auto-install

bunfig.toml

Debugger

Framework APISOON

Package manager

bun install

bun add

bun remove

bun update

bun publish

bun outdated

bun link

bun pm

Global cache

Workspaces

Lifecycle scripts

Filter

Lockfile

Scopes and registries

Overrides and resolutions

Patch dependencies

.npmrc support

Bundler

Bun.build

HTML & static sites

CSS

Fullstack Dev Server

Hot reloading

Loaders

Plugins

Macros

vs esbuild

Test runner

bun test

Writing tests

Watch mode

Lifecycle hooks

Mocks

Snapshots

Dates and times

DOM testing

Code coverage

Package runner

bunx

API

HTTP server

HTTP client

WebSockets

Workers

Binary data

Streams

SQL

S3 Object Storage

File I/O

import.meta

SQLite

FileSystemRouter

TCP sockets

UDP sockets

Globals

$ Shell

Child processes

HTMLRewriter

Hashing

Console

FFI

C Compiler

Testing

Utils

Node-API

Glob

DNS

Semver

Color

Transpiler

Project

Roadmap

Benchmarking

Contributing

Building Windows

Bindgen

License

File types

Edit on GitHub

TypeScript

Bun natively supports TypeScript out of the box. All files are transpiled on the fly by Bun's fast native transpiler before being executed. Similar to other build tools, Bun does not perform typechecking; it simply removes type annotations from the file.

bun index.js

bun index.jsx

bun index.ts

bun index.tsx

Some aspects of Bun's runtime behavior are affected by the contents of yourtsconfig.json file. Refer toRuntime > TypeScript page for details.

JSX

Bun supports.jsx and.tsx files out of the box. Bun's internal transpiler converts JSX syntax into vanilla JavaScript before execution.

react.tsx

functionComponent(props: {message:string}) {return (    <body>      <h1style={{color:'red'}}>{props.message}</h1>    </body>  );}console.log(<Componentmessage="Hello world!" />);

Bun implements special logging for JSX to make debugging easier.

bun run react.tsx

<Component message="Hello world!" />

Text files

Text files can be imported as strings.

index.ts

text.txt

index.ts

import textfrom"./text.txt";console.log(text);// => "Hello world!"

text.txt

Hello world!

JSON and TOML

JSON and TOML files can be directly imported from a source file. The contents will be loaded and returned as a JavaScript object.

import pkgfrom"./package.json";import datafrom"./data.toml";

WASI

🚧Experimental

Bun has experimental support for WASI, theWebAssembly System Interface. To run a.wasm binary with Bun:

bun ./my-wasm-app.wasm

# if the filename doesn't end with ".wasm"

bun run ./my-wasm-app.whatever

Note — WASI support is based onwasi-js. Currently, it only supports WASI binaries that use thewasi_snapshot_preview1 orwasi_unstable APIs. Bun's implementation is not fully optimized for performance; this will become more of a priority as WASM grows in popularity.

SQLite

You can import sqlite databases directly into your code. Bun will automatically load the database and return aDatabase object.

import dbfrom"./my.db" with { type: "sqlite" };console.log(db.query("select * from users LIMIT 1").get());

This usesbun:sqlite.

Custom loaders

Support for additional file types can be implemented with plugins. Refer toRuntime > Plugins for full documentation.

bun run

TypeScript

Edit on GitHub

Movatterモバイル変換

TypeScript

JSX

Text files

JSON and TOML

WASI

SQLite

Custom loaders