nodejs-express

Node.js + Express Development

Overview

Express.js is a minimal, flexible Node.js web application framework providing robust features for building web and mobile applications.

Project Structure

src/
├── index.ts              # Entry point
├── app.ts                # Express app setup
├── routes/
│   ├── index.ts          # Route aggregator
│   ├── auth.routes.ts    # Auth endpoints
│   └── user.routes.ts    # User endpoints
├── controllers/
│   ├── auth.controller.ts
│   └── user.controller.ts
├── services/
│   ├── auth.service.ts
│   └── user.service.ts
├── middleware/
│   ├── auth.middleware.ts
│   ├── error.middleware.ts
│   └── validation.middleware.ts
├── models/               # Database models
├── utils/
│   └── asyncHandler.ts   # Async error wrapper
└── types/
    └── index.ts          # TypeScript types

Core Patterns

App Setup

// src/app.ts
import express from 'express';
import cors from 'cors';
import helmet from 'helmet';
import { errorHandler } from './middleware/error.middleware';
import routes from './routes';

const app = express();

// Security middleware
app.use(helmet());
app.use(cors());

// Body parsing
app.use(express.json());
app.use(express.urlencoded({ extended: true }));

// Routes
app.use('/api/v1', routes);

// Error handling (must be last)
app.use(errorHandler);

export default app;

Async Handler Pattern

// src/utils/asyncHandler.ts
import { Request, Response, NextFunction } from 'express';

type AsyncFunction = (
  req: Request,
  res: Response,
  next: NextFunction
) => Promise<any>;

export const asyncHandler = (fn: AsyncFunction) => {
  return (req: Request, res: Response, next: NextFunction) => {
    Promise.resolve(fn(req, res, next)).catch(next);
  };
};

Controller Pattern

// src/controllers/user.controller.ts
import { Request, Response } from 'express';
import { asyncHandler } from '../utils/asyncHandler';
import * as userService from '../services/user.service';

export const getUsers = asyncHandler(async (req: Request, res: Response) => {
  const users = await userService.findAll();
  res.json({ success: true, data: users });
});

export const getUserById = asyncHandler(async (req: Request, res: Response) => {
  const user = await userService.findById(req.params.id);
  if (!user) {
    res.status(404).json({ success: false, error: 'User not found' });
    return;
  }
  res.json({ success: true, data: user });
});