Overview

Validation and quality enforcement for Bun.js projects.

What This Jutsu Provides

Validation Hooks

• Bun Type Check: Runs Bun's build type checker to ensure TypeScript code is valid
• Fast Validation: Leverages Bun's exceptional performance for rapid feedback

Skills

This jutsu provides the following skills:

• bun-runtime: Working with Bun's runtime APIs including file I/O, HTTP servers, WebSockets, and native APIs
• bun-testing: Writing tests with Bun's built-in test runner, assertions, mocking, and snapshot testing
• bun-bundler: Bundling JavaScript/TypeScript code with Bun's fast bundler for different targets
• bun-package-manager: Managing dependencies with Bun's package manager, workspaces, and lockfiles
• bun-sqlite: Working with SQLite databases using Bun's built-in high-performance SQLite driver

Installation

Install with npx (no installation required):

han plugin install jutsu-bun

Usage

Once installed, this jutsu automatically validates your Bun code:

• When you finish a conversation with Claude Code
• When Claude Code agents complete their work
• Before commits (when combined with git hooks)

The validation runs bun build --target=bun --no-bundle to check for type errors without actually bundling your code.

Requirements

• Bun 1.0.0 or higher
• TypeScript (for type checking)

Why Bun?

Bun is an all-in-one JavaScript runtime and toolkit designed for speed:

• Fast Runtime: 3x faster than Node.js for many operations
• Built-in Tools: Bundler, test runner, package manager all included
• Web Standard APIs: First-class support for Web APIs like fetch, WebSocket
• TypeScript Native: Run TypeScript and JSX directly without transpilation
• npm Compatible: Works with existing npm packages
• SQLite Built-in: High-performance SQLite driver included

Features Covered by Skills

Runtime APIs

• File I/O with Bun.file() and Bun.write()
• HTTP servers with Bun.serve()
• WebSocket support
• Password hashing
• Environment variables
• Shell command execution with Bun.$

Testing

• Built-in test runner
• Jest-compatible API
• Mocking and spies
• Snapshot testing
• Coverage reporting
• Watch mode

Bundler

• Fast bundling for multiple targets (bun, browser, node)
• Tree shaking
• Code splitting
• Minification
• Source maps
• Plugin system

Package Manager

• Fast dependency installation
• Binary lockfile (bun.lockb)
• Workspace support for monorepos
• npm/yarn/pnpm compatibility
• Global packages
• Link local packages

SQLite

• Native SQLite driver
• Prepared statements
• Transactions
• Migration support
• High performance

Examples

Create a Simple HTTP Server

Bun.serve({
  port: 3000,
  fetch(req) {
    return new Response("Hello from Bun!");
  },
});

Run Tests

import { test, expect } from "bun:test";

test("addition", () => {
  expect(1 + 1).toBe(2);
});

Bundle Your Code

bun build src/index.ts --outdir dist --target browser --minify

Install Dependencies

bun add express
bun add -d @types/express

Use SQLite

import { Database } from "bun:sqlite";

const db = new Database("mydb.sqlite");
db.run("CREATE TABLE users (id INTEGER PRIMARY KEY, name TEXT)");
db.run("INSERT INTO users (name) VALUES (?)", ["Alice"]);