TypeScript 在 Node.js 中的实战应用

项目初始化

npm init -y
npm install -D typescript @types/node ts-node
npx tsc --init

{
  "compilerOptions": {
    "target": "ES2020",
    "module": "CommonJS",
    "outDir": "./dist",
    "rootDir": "./src",
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules", "dist"]
}

Express + TypeScript 实战

import express, { Request, Response, NextFunction } from 'express';
const app = express();
app.use(express.json());
interface User {
  id: number;
  name: string;
  email: string;
}
const users: User[] = [
  { id: 1, name: '张三', email: 'zhang@example.com' },
  { id: 2, name: '李四', email: 'li@example.com' },
];
app.get('/api/users', (req: Request, res: Response) => {
  res.json(users);
});
app.get('/api/users/:id', (req: Request, res: Response) => {
  const user = users.find(u => u.id === parseInt(req.params.id));
  if (!user) return res.status(404).json({ error: '用户不存在' });
  res.json(user);
});
app.post('/api/users', (req: Request, res: Response) => {
  const { name, email } = req.body as Omit;
  if (!name || !email) return res.status(400).json({ error: 'name 和 email 必填' });
  const newUser: User = { id: users.length + 1, name, email };
  users.push(newUser);
  res.status(201).json(newUser);
});
app.use((err: Error, req: Request, res: Response, next: NextFunction) => {
  console.error(err.stack);
  res.status(500).json({ error: '服务器内部错误' });
});
app.listen(3000, () => { console.log('服务运行在 http://localhost:3000'); });
export default app;

自定义类型中间件

import { Request, Response, NextFunction } from 'express';

declare global {
  namespace Express {
    interface Request {
      user?: { id: number; role: string };
      requestId?: string;
    }
  }
}
function auth(req: Request, res: Response, next: NextFunction) {
  const token = req.headers.authorization;
  if (!token) return res.status(401).json({ error: '未登录' });
  try {
    req.user = verifyToken(token);
    next();
  } catch {
    res.status(401).json({ error: 'Token 无效' });
  }
}
app.get('/api/protected', auth, (req: Request, res: Response) => {
  res.json({ message: '受保护的资源', user: req.user });
});

数据库操作类型安全

interface QueryResult {
  rows: T[];
  rowCount: number;
}

async function query(sql: string, params: any[] = []): Promise {
  const { rows } = await pool.query(sql, params);
  return rows as T[];
}
interface UserRow {
  id: number;
  name: string;
  created_at: Date;
}
async function getUsers(): Promise {
  return query('SELECT id, name, created_at FROM users LIMIT 50');
}
async function getUserById(id: number): Promise {
  const results = await query(
    'SELECT id, name, created_at FROM users WHERE id = $1', [id]
  );
  return results[0] ?? null;
}

常用脚本配置

{
  "scripts": {
    "dev": "ts-node src/app.ts",
    "build": "tsc",
    "start": "node dist/app.js",
    "typecheck": "tsc --noEmit"
  }
}