CheatPress

Bun JS runtime and toolkit

Version 1.4.3 · source

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Start here

bun init
Scaffold a project
bun install
Install dependencies
bun add <pkg>
Add a dependency
bun run <script>
Run a package script
bun <file>
Run a TS or JS file
bun test
Run the tests
bun build <entry> --outdir <dir>
Bundle for output
bunx <pkg>
Run a package binary

Concepts

  1. package.json declared ranges
  2. bun.lock pinned versions
  3. node_modules global cache
  4. Your code TS, JSX, JS

Install and add

bun install
Install all dependencies
bun add <pkg>
Add a dependency
bun add <pkg>@<version>
Add a specific version or tag
bun add -d <pkg>
Add a dev dependency
bun add --exact <pkg>
Pin the exact version
bun add --optional <pkg>
Add an optional dependency
bun add --peer <pkg>
Add a peer dependency
bun add github:<user>/<repo>
Add from a GitHub repo
bun add -g <pkg>
Install a CLI tool globally
bun install --frozen-lockfile
Fail if lockfile is out of date
bun ci
Same as install --frozen-lockfile
bun install --production
Skip devDependencies
Also implies --frozen-lockfile.
bun install --filter <pattern>
Install only for matching workspaces
bun install --linker isolated
Use isolated node_modules layout
bun install --dry-run
Resolve without installing
bun install --ignore-scripts
Skip all lifecycle scripts

Remove and update

bun remove <pkg>
Remove a dependency
bun update
Update within package.json ranges
bun update <pkg>
Update one package
bun update --latest
Ignore ranges, take latest
bun update -i
Pick updates interactively
bun update -r
Update every workspace
bun outdated
Show packages with newer versions
bun outdated '<glob>'
Check only matching packages
bun audit
Check for known vulnerabilities
bun audit --audit-level=high
Report only high severity and up
bun audit fix
Upgrade vulnerable packages

Run and watch

bun <file>
Run a TS, JS or JSX file
bun run <script>
Run a package.json script
bun run
List available scripts
bun --watch <file>
Restart on file change
bun --hot <file>
Reload in place, keep state
bun --env-file=<file> <file>
Load a specific .env file
bun run --bun <bin>
Run a Node-shebang binary with Bun
bun run --silent <script>
Do not echo the script command
bun run --if-present <script>
No error if the script is missing
bun -e '<code>'
Evaluate a code string
bun --inspect <file>
Run with the debugger on
bunx <pkg>
Run a package binary without installing
bunx <pkg>@<version>
Run a specific version
bunx -p <pkg> <bin>
Binary name differs from package
bunx --bun <pkg>
Run with Bun instead of Node

Test

bun test
Run all tests
bun test <path>
Run files matching a path filter
bun test -t '<regex>'
Run tests by name pattern
bun test --watch
Re-run on file change
bun test --coverage
Print a coverage report
bun test --bail
Stop at the first failure
bun test --timeout <ms>
Set per-test timeout
Default is 5000 ms.
bun test -u
Update snapshots
bun test --rerun-each <n>
Repeat files to find flaky tests
bun test --randomize
Shuffle test order
bun test --concurrent
Run tests concurrently
bun test --coverage-reporter lcov
Write lcov coverage
bun test --reporter junit --reporter-outfile <file>
Write a JUnit XML report

Build and scaffold

bun init -y
Scaffold with default answers
bun init --react
Scaffold a React app
bun build <entry> --outdir <dir>
Bundle to a directory
bun build <entry> --outfile <file>
Bundle to one file
bun build <entry> --compile --outfile <name>
Make a standalone executable
bun build <entry> --target <env>
Target browser, bun or node
bun build <entry> --minify
Minify the output
bun build <entry> --sourcemap=linked
Emit source maps
bun build <entry> --external <pkg>
Leave a package out of the bundle
bun build <entry> --splitting
Split shared code into chunks
bun build <entry> --watch
Rebuild on change

Workspaces and packages

bun run --filter '<pattern>' <script>
Run a script in matching workspaces
bun run --workspaces <script>
Run a script in all workspaces
bun run --parallel <script> <script>
Run scripts concurrently
bun add <pkg> --filter <workspace>
Add a dependency to one workspace
bun add <pkg> --catalog
Record the version in the root catalog
bun link
Register this package for linking
bun link <pkg>
Link a registered package here
bun pm ls
List top-level installed packages
bun pm ls --all
Include nested dependencies
bun why <pkg>
Explain why a package is installed
bun pm untrusted
List blocked lifecycle scripts
bun pm trust <pkg>
Run blocked scripts and trust a package
bun pm cache
Show the global cache path
bun pm cache rm
Clear the global cache
bun pm version patch
Bump the package version
bun pm pack
Create the publish tarball
Workspaces in package.json
"workspaces": {  "packages": ["packages/*"],  "catalog": { "react": "^19.0.0" }}// in a package: "react": "catalog:"
Allow a dependency script
"trustedDependencies": ["esbuild"]# then reinstall, or: bun pm trust esbuild

Recipes

Start a TypeScript project
bun init -ybun add zodbun add -d @types/nodebun --watch index.ts
CI install and test
bun cibun test --bailbun run build
Ship a single binary
bun build ./cli.ts --compile --outfile mycli./mycli --help
Monorepo: one workspace
bun installbun add zod --filter apibun run --filter api dev