TypeScript в Node.js: настройка и преимущества

1npm install -D typescript @types/node ts-node
2npx tsc --init

1{
2  "compilerOptions": {
3    "target": "ES2020",
4    "module": "commonjs",
5    "lib": ["ES2020"],
6    "outDir": "./dist",
7    "rootDir": "./src",
8    "strict": true,
9    "esModuleInterop": true,
10    "skipLibCheck": true,
11    "forceConsistentCasingInFileNames": true,
12    "resolveJsonModule": true,
13    "declaration": true,
14    "declarationMap": true,
15    "sourceMap": true
16  },
17  "include": ["src/**/*"],
18  "exclude": ["node_modules", "dist"]
19}

1{
2  "compilerOptions": {
3    "strict": true
4  }
5}

1interface User {
2  id: number;
3  name: string;
4  email: string;
5  role: 'admin' | 'user';
6}
7
8type CreateUserDTO = Omit<User, 'id'>;

1enum Status {
2  Active = 'ACTIVE',
3  Inactive = 'INACTIVE',
4  Deleted = 'DELETED',
5}

1function identity<T>(arg: T): T {
2  return arg;
3}
4
5interface ApiResponse<T> {
6  data: T;
7  status: number;
8  message: string;
9}

1import express, { Request, Response, NextFunction } from 'express';
2
3const app = express();
4
5app.get('/users/:id', (req: Request<{ id: string }>, res: Response) => {
6  const { id } = req.params;
7  res.json({ id: parseInt(id) });
8});
9
10app.post('/users', (req: Request<{}, {}, CreateUserDTO>, res: Response) => {
11  const user = req.body;
12  // user типизирован
13});
14
15// Middleware с типами
16interface AppError extends Error {
17  statusCode: number;
18}
19
20function errorHandler(err: AppError, req: Request, res: Response, next: NextFunction) {
21  res.status(err.statusCode || 500).json({ error: err.message });
22}

1{
2  "compilerOptions": {
3    "baseUrl": ".",
4    "paths": {
5      "@/*": ["src/*"],
6      "@config/*": ["src/config/*"],
7      "@services/*": ["src/services/*"]
8    }
9  }
10}

1import { db } from '@/config/database';
2import { UserService } from '@/services/user.service';

1npx ts-node src/index.ts

1npx tsc
2node dist/index.js

1npm install -D tsx
2npx tsx src/index.ts

1interface UserRepository {
2  findById(id: number): Promise<User | null>;
3  create(data: CreateUserDTO): Promise<User>;
4  update(id: number, data: Partial<User>): Promise<User>;
5  delete(id: number): Promise<void>;
6}
7
8class PrismaUserRepository implements UserRepository {
9  async findById(id: number): Promise<User | null> {
10    return prisma.user.findUnique({ where: { id } });
11  }
12  // ...
13}

1class UserService {
2  constructor(private userRepo: UserRepository) {}
3
4  async getUser(id: number): Promise<User | null> {
5    return this.userRepo.findById(id);
6  }
7}

1// Плохо
2function process(data: any): any { }
3
4// Хорошо
5function process(data: User): Response { }

1function isUser(obj: any): obj is User {
2  return obj && typeof obj.id === 'number' && typeof obj.name === 'string';
3}