Get Started

Welcome to Bun Installation Quickstart TypeScript TypeScript 6 and 7

Watch Mode Debugging REPL bunfig.toml File Types Module Resolution JSX Auto-install Plugins File System Router

Cookies File I/O Streams Binary Data Archive SQL SQLite S3 Redis Workers Environment Variables Shell Spawn WebView Cron Node-API FFI C Compiler Transpiler CSRF Protection Secrets Console TOML YAML Markdown JSON5 JSONL HTMLRewriter Image Hashing Glob Semver Color Utils Globals Bun APIs Web APIs Node.js Compatibility

Install TypeScript declarations for Bun Re-map import paths Debugging Bun with the VS Code extension Debugging Bun with the web debugger Inspect memory usage using V8 heap snapshots Build-time constants with --define Define and replace static globals & constants Install and run Bun in GitHub Actions Codesign a single-file JavaScript executable on macOS

File SystemRuntime & Debugging

Define and replace static globals & constants

The --define flag declares statically-analyzable constants and globals. It replaces all usages of an identifier or property in a JavaScript or TypeScript file

Build-time constants with --define

Pass --define to bun build or bun build --compile to inject build-time constants into your application. Use it to embed metadata like build versions,

Install and run Bun in GitHub Actions

Use the official setup-bun GitHub Action to install bun in your GitHub Actions runner.

On this page

What types of values are supported?Replace global identifiers Replace values with JSON Replace values with other properties How is this different than setting a variable?How is this different than find-and-replace or string replacement?