From bun
Provides guidance and examples for Bun runtime APIs including Bun.file(), Bun.serve(), WebSockets, environment variables, and shell execution in JS/TS projects.
npx claudepluginhub thebushidocollective/han --plugin bunThis skill is limited to using the following tools:
Use this skill when working with Bun's runtime environment, including file system operations, HTTP servers, environment variables, and Bun-specific APIs.
Guides fast JavaScript/TypeScript development with Bun runtime: project init, package management, built-in bundler/test runner, Node.js migration, and troubleshooting.
Guides Bun runtime usage including CLI flags (--watch, --hot), watch/hot modes, env vars and .env files, bunfig.toml config, package.json scripts, and module resolution.
Share bugs, ideas, or general feedback.
Use this skill when working with Bun's runtime environment, including file system operations, HTTP servers, environment variables, and Bun-specific APIs.
Bun provides several global APIs that are optimized for performance:
Bun.file() - Fast file reading with automatic content-type detectionBun.write() - High-performance file writingBun.serve() - Ultra-fast HTTP serverBun.env - Type-safe environment variablesBun.$ - Shell command execution with template literalsBun's file APIs are significantly faster than Node.js equivalents:
// Reading files
const file = Bun.file("./data.json");
const text = await file.text();
const json = await file.json();
const arrayBuffer = await file.arrayBuffer();
// Writing files
await Bun.write("output.txt", "Hello, Bun!");
await Bun.write("data.json", { key: "value" });
// Streaming large files
const file = Bun.file("large-file.txt");
const stream = file.stream();
Bun.serve() provides exceptional performance:
Bun.serve({
port: 3000,
fetch(req) {
const url = new URL(req.url);
if (url.pathname === "/") {
return new Response("Hello, Bun!");
}
if (url.pathname === "/api/data") {
return Response.json({ message: "Fast API response" });
}
return new Response("Not Found", { status: 404 });
},
});
Built-in WebSocket support without external dependencies:
Bun.serve({
port: 3000,
fetch(req, server) {
if (server.upgrade(req)) {
return; // WebSocket upgrade successful
}
return new Response("Expected WebSocket connection", { status: 400 });
},
websocket: {
message(ws, message) {
console.log("Received:", message);
ws.send(`Echo: ${message}`);
},
open(ws) {
console.log("Client connected");
},
close(ws) {
console.log("Client disconnected");
},
},
});
Prefer Bun's native APIs over Node.js equivalents for better performance:
// Good - Use Bun.file()
const data = await Bun.file("./data.json").json();
// Avoid - Don't use fs from Node.js when Bun alternatives exist
import fs from "fs/promises";
const data = JSON.parse(await fs.readFile("./data.json", "utf-8"));
Use type-safe environment variable access:
// Good - Type-safe access
const apiKey = Bun.env.API_KEY;
// Also valid - process.env works but Bun.env is preferred
const port = process.env.PORT ?? "3000";
Use Bun.$ for shell command execution:
// Execute shell commands safely
import { $ } from "bun";
const output = await $`ls -la`.text();
const gitBranch = await $`git branch --show-current`.text();
// With error handling
try {
await $`npm run build`;
} catch (error) {
console.error("Build failed:", error);
}
Use built-in password hashing:
const password = "super-secret";
// Hash a password
const hash = await Bun.password.hash(password);
// Verify a password
const isMatch = await Bun.password.verify(password, hash);
interface User {
id: number;
name: string;
}
const users: User[] = [
{ id: 1, name: "Alice" },
{ id: 2, name: "Bob" },
];
Bun.serve({
port: 3000,
fetch(req) {
const url = new URL(req.url);
if (url.pathname === "/api/users") {
return Response.json(users);
}
if (url.pathname.startsWith("/api/users/")) {
const id = parseInt(url.pathname.split("/")[3]);
const user = users.find((u) => u.id === id);
if (!user) {
return Response.json({ error: "User not found" }, { status: 404 });
}
return Response.json(user);
}
return Response.json({ error: "Not found" }, { status: 404 });
},
});
Bun.serve({
port: 3000,
async fetch(req) {
if (req.method === "POST" && new URL(req.url).pathname === "/upload") {
const formData = await req.formData();
const file = formData.get("file") as File;
if (!file) {
return Response.json({ error: "No file provided" }, { status: 400 });
}
await Bun.write(`./uploads/${file.name}`, file);
return Response.json({
message: "File uploaded successfully",
filename: file.name,
size: file.size,
});
}
return new Response("Method not allowed", { status: 405 });
},
});
// Read and parse JSON config
const config = await Bun.file("./config.json").json();
// Read TOML (Bun has built-in TOML support)
const tomlConfig = await Bun.file("./config.toml").text();
// Read environment-specific config
const env = Bun.env.NODE_ENV ?? "development";
const envConfig = await Bun.file(`./config.${env}.json`).json();
// Bad - Mixing APIs without reason
import fs from "fs/promises";
const data1 = await fs.readFile("file1.txt", "utf-8");
const data2 = await Bun.file("file2.txt").text();
// Good - Use consistent APIs
const data1 = await Bun.file("file1.txt").text();
const data2 = await Bun.file("file2.txt").text();
// Bad - No error handling
const data = await Bun.file("./might-not-exist.json").json();
// Good - Proper error handling
try {
const file = Bun.file("./might-not-exist.json");
if (await file.exists()) {
const data = await file.json();
} else {
console.error("File not found");
}
} catch (error) {
console.error("Failed to read file:", error);
}
// Bad - Synchronous file reading blocks
import fs from "fs";
const data = fs.readFileSync("large-file.txt", "utf-8");
// Good - Async operations
const data = await Bun.file("large-file.txt").text();