bun run

The bun CLI can be used to execute JavaScript/TypeScript files, package.json scripts, and executable packages.

Running a file

Compare to node <file>

Bun can execute .js, .jsx, .ts, and .tsx files. Every file is transpiled to vanilla JavaScript by Bun's fast native transpiler before being executed. For details on Bun's runtime, refer to the Bun runtime documentation.

import { z } from "zod";

const schema = z.string()
const result = schema.parse("Billie Eilish");

To run a file in Bun:

bun foo.ts
Billie Eilish

If no node_modules directory is found in the working directory or above, Bun will abandon Node.js-style module resolution in favor of the Bun module resolution algorithm. Under Bun-style module resolution, all packages are auto-installed on the fly into a global module cache. For full details on this algorithm, refer to Runtime > Modules.

Running a package script

Compare to npm run <script> or yarn <script>

Your package.json can define a number of named "scripts" that correspond to shell commands.

  // ... other fields
  "scripts": {
    "clean": "rm -rf dist && echo 'Done.'",
    "dev": "bun server.ts"

Use bun <script> to execute these scripts.

bun clean
 $ rm -rf dist && echo 'Done.'

Bun executes the script command in a subshell. It checks for the following shells in order, using the first one it finds: bash, sh, zsh.

⚡️ The startup time for npm run on Linux is roughly 170ms; with Bun it is 6ms.

If there is a name conflict between a package.json script and a built-in bun command (install, dev, upgrade, etc.) Bun's built-in command takes precedence. In this case, use the more explicit bun run command to execute your package script.

bun run dev

To see a list of available scripts, run bun run without any arguments.

bun run
quickstart scripts:

 bun run clean
   rm -rf dist && echo 'Done.'

 bun run dev
   bun server.ts

2 scripts

Bun respects lifecycle hooks. For instance, bun run clean will execute preclean and postclean, if defined. If the pre<script> fails, Bun will not execute the script itself.