Express.js Coding Standards - mhmunem/Grocery-Comparison-App GitHub Wiki

A well-organized folder structure improves code readability and maintainability. Here's the recommended structure:

├── src/ # Main application code
│ ├── config/ # Configuration files (e.g., environment, database)
│ ├── controllers/ # Business logic for routes
│ ├── middlewares/ # Custom middleware functions
│ ├── models/ # ORM or database models
│ ├── routes/ # API route definitions
│ ├── services/ # Service layer (reusable business logic)
│ ├── utils/ # Helper utilities (e.g., error handlers, logging)
│ └── app.js # Express app initialization
├── .env # Environment variables
├── server.js # Entry point for the application
├── .gitignore # Files and folders to ignore in Git
├── package.json # Project dependencies and scripts
└── README.md # Documentation\

• Store sensitive information (API keys, database credentials) in a .env file.

• Use the dotenv package to load environment variables:

  require('dotenv').config();  
  const PORT = process.env.PORT || 3000;  
  

• Follow the Model-View-Controller (MVC) pattern to separate concerns.
• Controllers handle request-response logic.
• Models interact with the database.
• Routes define API endpoints.

Example:

• Controller (productController.js)
• Service (productService.js)
• Route (productRoutes.js)

• Centralize error handling to avoid duplicating error-handling logic.
• use middleware folder for Error Handling: for eg: src/middlewares/errorHandler.js

use in app.js:

const errorHandler = require('./middlewares/errorHandler');  
app.use(errorHandler);  

• Use libraries such as express-validator or some to validate and sanitize input.

const { body, validationResult } = require('express-validator');  

• Avoid callback hell and improve readability by using async/await.

Bad Practice:

product.find({}, (err, products) => {  
    if (err) {  
        return res.status(500).send(err);  
    }  
    res.send(products);  
});  

Good Practice:

const products = await product.find();  
res.send(products);  

• Use the helmet middleware to secure HTTP headers.

  const helmet = require('helmet');  
  app.use(helmet());  
  

• Use cors to configure cross-origin resource sharing.

• Use a logging library for better insight.
• Use docstring
• check for outdated dependencies.
• Regularly update dependencies to avoid vulnerabilities.
• Naming Conventions:
  • Use camelCase for variables and functions.
  • Use PascalCase for classes.
  • Name files descriptively (productController.js, not pro.js).
• Linting:
  • Use eslint to enforce consistent code style.
• Code Reviews:
  • Ensure every pull request is reviewed before merging to maintain quality.