Hello World - 第一个程序 #

# 直接执行代码
bun -e "console.log('Hello, Bun!')"

# 输出
# Hello, Bun!

# 创建项目目录
mkdir my-bun-app
cd my-bun-app

# 创建入口文件
echo "console.log('Hello, Bun!');" > index.js

# 运行
bun run index.js

# 输出
# Hello, Bun!

// index.js
console.log("Hello, Bun!");

// 变量声明
const name = "Bun";
const version = 1.2;

console.log(`Welcome to ${name} v${version}!`);

bun run index.js

// math.js
export function add(a, b) {
  return a + b;
}

export function multiply(a, b) {
  return a * b;
}

// index.js
import { add, multiply } from "./math.js";

console.log("1 + 2 =", add(1, 2));
console.log("3 * 4 =", multiply(3, 4));

// math.cjs
function add(a, b) {
  return a + b;
}

function multiply(a, b) {
  return a * b;
}

module.exports = { add, multiply };

// index.cjs
const { add, multiply } = require("./math.cjs");

console.log("1 + 2 =", add(1, 2));
console.log("3 * 4 =", multiply(3, 4));

// index.ts
interface User {
  name: string;
  age: number;
}

function greet(user: User): string {
  return `Hello, ${user.name}! You are ${user.age} years old.`;
}

const user: User = {
  name: "Bun",
  age: 3,
};

console.log(greet(user));

# 直接运行，无需编译
bun run index.ts

// types.ts
export interface Product {
  id: number;
  name: string;
  price: number;
}

export type Status = "pending" | "completed" | "cancelled";

// index.ts
import type { Product, Status } from "./types";

const product: Product = {
  id: 1,
  name: "Bun Book",
  price: 29.99,
};

const status: Status = "completed";

console.log(product, status);

// utils.ts
export function identity<T>(arg: T): T {
  return arg;
}

export function first<T>(arr: T[]): T | undefined {
  return arr[0];
}

export function map<T, U>(arr: T[], fn: (item: T) => U): U[] {
  return arr.map(fn);
}

// index.ts
import { identity, first, map } from "./utils";

console.log(identity<string>("Hello"));
console.log(first([1, 2, 3]));
console.log(map([1, 2, 3], (x) => x * 2));

// app.tsx
function Button({ children, onClick }: { 
  children: string; 
  onClick?: () => void 
}) {
  return (
    <button 
      onClick={onClick}
      style={{ padding: "10px 20px", fontSize: "16px" }}
    >
      {children}
    </button>
  );
}

function App() {
  const handleClick = () => console.log("Button clicked!");
  
  return (
    <div>
      <h1>Hello, Bun + React!</h1>
      <Button onClick={handleClick}>Click Me</Button>
    </div>
  );
}

// 渲染为字符串
console.log(<App />);

bun run app.tsx

{
  "compilerOptions": {
    "jsx": "react-jsx",
    "jsxImportSource": "react"
  }
}

{
  "compilerOptions": {
    "jsx": "react-jsx",
    "jsxImportSource": "preact"
  }
}

// server.ts
Bun.serve({
  port: 3000,
  fetch(req) {
    const url = new URL(req.url);
    
    if (url.pathname === "/") {
      return new Response("Hello, Bun!");
    }
    
    if (url.pathname === "/json") {
      return Response.json({ message: "Hello, JSON!" });
    }
    
    return new Response("Not Found", { status: 404 });
  },
});

console.log("Server running at http://localhost:3000");

bun run server.ts

# 访问 http://localhost:3000

// router.ts
const routes: Record<string, () => Response> = {
  "/": () => new Response("Home Page"),
  "/about": () => new Response("About Page"),
  "/api/status": () => Response.json({ status: "ok", time: Date.now() }),
};

Bun.serve({
  port: 3000,
  fetch(req) {
    const url = new URL(req.url);
    const handler = routes[url.pathname];
    
    if (handler) {
      return handler();
    }
    
    return new Response("Not Found", { status: 404 });
  },
});

console.log("Server running at http://localhost:3000");

# 使用 --hot 参数实现热重载
bun --hot run server.ts

// server.ts
Bun.serve({
  port: 3000,
  fetch(req) {
    return new Response(`Server started at ${new Date().toISOString()}`);
  },
});

console.log("Server running at http://localhost:3000");

// read.ts
// 方式一：使用 Bun.file()
const file = Bun.file("./data.txt");
const text = await file.text();
console.log(text);

// 方式二：使用 Bun.read()
const content = await Bun.read("./data.txt");
console.log(content);

// 方式三：读取 JSON
const data = await Bun.file("./data.json").json();
console.log(data);

// write.ts
// 方式一：使用 Bun.write()
await Bun.write("./output.txt", "Hello, Bun!");

// 方式二：写入 JSON
await Bun.write("./output.json", JSON.stringify({ name: "Bun" }));

// 方式三：写入 Buffer
const buffer = new TextEncoder().encode("Hello, Buffer!");
await Bun.write("./buffer.txt", buffer);

// watch.ts
const watcher = Bun.watch("./", {
  recursive: true,
});

watcher.on("change", (event, filename) => {
  console.log(`File changed: ${filename}`);
  console.log(`Event: ${event}`);
});

console.log("Watching for changes...");

// database.ts
import { Database } from "bun:sqlite";

// 创建内存数据库
const db = new Database(":memory:");

// 创建表
db.run(`
  CREATE TABLE users (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    name TEXT NOT NULL,
    email TEXT UNIQUE
  )
`);

// 插入数据
db.run("INSERT INTO users (name, email) VALUES (?, ?)", ["Bun", "bun@example.com"]);
db.run("INSERT INTO users (name, email) VALUES (?, ?)", ["User", "user@example.com"]);

// 查询数据
const users = db.query("SELECT * FROM users").all();
console.log(users);

// 查询单条
const user = db.query("SELECT * FROM users WHERE id = ?").get(1);
console.log(user);

// 关闭数据库
db.close();

// orm.ts
import { Database } from "bun:sqlite";

const db = new Database(":memory:");

// 创建表
db.run(`
  CREATE TABLE products (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    name TEXT NOT NULL,
    price REAL
  )
`);

// 预编译语句
const insertStmt = db.prepare("INSERT INTO products (name, price) VALUES ($name, $price)");
const selectStmt = db.prepare("SELECT * FROM products WHERE price > $minPrice");

// 批量插入
const insertMany = db.transaction((products) => {
  for (const product of products) {
    insertStmt.run(product);
  }
});

insertMany([
  { $name: "Apple", $price: 1.5 },
  { $name: "Banana", $price: 2.0 },
  { $name: "Orange", $price: 1.8 },
]);

// 查询
const expensiveProducts = selectStmt.all({ $minPrice: 1.5 });
console.log(expensiveProducts);

db.close();

// fetch.ts
// GET 请求
const response = await fetch("https://jsonplaceholder.typicode.com/posts/1");
const post = await response.json();
console.log(post);

// POST 请求
const createResponse = await fetch("https://jsonplaceholder.typicode.com/posts", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    title: "Bun Post",
    body: "Hello from Bun!",
    userId: 1,
  }),
});
const newPost = await createResponse.json();
console.log(newPost);

// websocket.ts
const ws = new WebSocket("wss://echo.websocket.org");

ws.onopen = () => {
  console.log("Connected!");
  ws.send("Hello, WebSocket!");
};

ws.onmessage = (event) => {
  console.log("Received:", event.data);
};

ws.onerror = (error) => {
  console.error("Error:", error);
};

ws.onclose = () => {
  console.log("Disconnected");
};

# 初始化项目
bun init

# 或手动创建
touch package.json

{
  "name": "my-bun-app",
  "version": "1.0.0",
  "type": "module",
  "scripts": {
    "start": "bun run index.ts",
    "dev": "bun --hot run index.ts",
    "test": "bun test",
    "build": "bun build ./src/index.ts --outdir ./dist"
  },
  "dependencies": {},
  "devDependencies": {
    "bun-types": "latest"
  }
}

# 运行 start 脚本
bun start

# 运行 dev 脚本
bun dev

# 运行测试
bun test

my-bun-app/
├── src/
│   ├── index.ts        # 入口文件
│   ├── routes/
│   │   └── api.ts
│   ├── utils/
│   │   └── helpers.ts
│   └── types/
│       └── index.ts
├── tests/
│   └── index.test.ts
├── public/
│   └── index.html
├── package.json
├── tsconfig.json
└── bunfig.toml

// src/index.ts
import { serveAPI } from "./routes/api";
import { logger } from "./utils/helpers";

const PORT = process.env.PORT || 3000;

Bun.serve({
  port: PORT,
  fetch: serveAPI,
});

logger(`Server running at http://localhost:${PORT}`);