Five clean coding best practices in Node.js

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Tech Tonic

9 min readMay 23, 2024

In this article, we’ll go over the top 5 clean coding best practices that can be followed by Node.js beginners. Without further delay, let’s get started.

Clean coding best practice 1 — Modularize your code

Modularizing your code is a fundamental best practice in software development, and Node.js is no exception. Modular code is divided into smaller, independent modules, each with a specific responsibility. This approach has numerous benefits, such as:

Easier maintenance: With modular code, you can modify or update individual modules without affecting the entire application.
Improved reusability: Modular code allows you to reuse modules across different projects or applications.
Faster development: Modular code enables you to work on different modules simultaneously, speeding up the development process.
Better organization: Modular code promotes a clear and organized structure, making it easier to understand and navigate.

In Node.js, modularization is achieved using the exports and require statements. Here's a brief overview:

exports: Exports a module’s functionality, making it available for other modules to use.
require: Imports a module’s functionality, allowing you to use its exported features.

Let’s dive into some code samples to illustrate modularization in Node.js!

Sample 1: Simple Module

There is a module called mathUtils.js:

// mathUtils.js
exports.add = (a, b) => a + b;
exports.multiply = (a, b) => a * b;

In this example, we’re exporting two functions, add and multiply, from the mathUtils module.

Sample 2: Using Modules

There is a file called calculator.js:

// calculator.js
const mathUtils = require('./mathUtils');

console.log(mathUtils.add(2, 3)); // Output: 5
console.log(mathUtils.multiply(4, 5)); // Output: 20

Here, we’re importing the mathUtils module and using its exported functions, add and multiply.

Sample 3: Modularizing a Larger Application

Suppose we’re building a simple blog application with the following structure:

blog-app/
  app.js
  models/
    user.js
    post.js
  controllers/
    userController.js
    postController.js
  utils/
    stringUtils.js

In this example, we’ve divided the application into separate modules:

models: Contains data models for users and posts.
controllers: Handles user and post-related logic.
utils: Utility functions for string manipulation.

Each module is self-contained and exports specific functionality. For instance, userController.js might import the user model and use its exported functions:

// userController.js
const User = require('../models/user');

exports.getUser = (id) => {
  return User.findById(id);
};

By modularizing our code, we’ve made it easier to maintain, update, and scale our application.

Clean coding best practice 2 — Use consistent naming conventions

Consistent naming conventions are essential in software development, and Node.js is again no exception. Naming conventions help developers quickly understand the purpose and functionality of variables, functions, and modules. Inconsistent naming can lead to confusion, errors, and maintenance headaches.

Consistent naming conventions offer several benefits:

Readability: Consistent naming makes your code easy to read and understand, reducing the time spent deciphering variable and function names.
Maintainability: Consistent naming helps you identify and update code quickly, as you can easily recognize the purpose of variables and functions.
Collaboration: Consistent naming conventions facilitate teamwork, as developers can quickly understand each other’s code.
Error reduction: Inconsistent naming can lead to errors, such as mistyping variable names or using the wrong function. Consistent naming reduces these errors.

Node.js Naming Conventions

Node.js follows the JavaScript naming conventions, which recommend:

CamelCase: Use camelCase for variable and function names (e.g., userName, getUserData).
PascalCase: Use PascalCase for class and constructor names (e.g., UserData, UserManager).
Underscores: Use underscores for file and directory names (e.g., user_controller.js, utils/string_utils.js).

Sample 1: Consistent Variable Naming

Compare these two examples:

// Inconsistent naming
let user_name = 'John';
let UserName = 'Jane';

// Consistent naming
let userName = 'John';
let userSurname = 'Doe';

In the first example, the variable names are inconsistent, using both camelCase and PascalCase. In the second example, we use consistent camelCase naming for both variables.

Sample 2: Consistent Function Naming

Compare these two examples:

// Inconsistent naming
function getUser() {}
function GetUserData() {}

// Consistent naming
function getUserData() {}
function getUserDetails() {}

In the first example, the function names are inconsistent, using both camelCase and PascalCase. In the second example, we use consistent camelCase naming for both functions.

Sample 3: Consistent File and Directory Naming

Compare these two examples:

// Inconsistent naming
userController.js
Utils/String_Utils.js

// Consistent naming
user_controller.js
utils/string_utils.js

In the first example, the file and directory names are inconsistent, using both camelCase and underscores. In the second example, we use consistent underscore naming for both file and directory names.

Consistent naming conventions are crucial in Node.js development. By following established naming conventions, you’ll write more readable, maintainable, and efficient code. Remember to use camelCase for variable and function names, PascalCase for class and constructor names, and underscores for file and directory names.

Clean coding best practice 3 — Write clean and concise functions

Functions are the building blocks of your code, and well-structured functions make your code efficient, readable, and maintainable. In this best practice, we’ll explore the importance of clean and concise functions and provide code samples to illustrate best practices.

Clean and concise functions offer several benefits:

Efficiency: Short and focused functions reduce execution time and memory usage.
Readability: Well-structured functions are easy to understand, making your code more readable.
Maintainability: Concise functions are easier to update and modify, reducing maintenance time.
Reusability: Clean functions can be reused throughout your codebase, reducing duplication.

Characteristics of clean and concise functions

Clean and concise functions typically have:

Single responsibility: Each function has a single, well-defined purpose.
Short length: Functions are brief, ideally between 5–10 lines of code.
Clear naming: Function names accurately describe their purpose.
Minimal parameters: Functions have few parameters, making them easier to understand.
Early returns: Functions use early returns to reduce nesting and improve readability.

Sample 1: Refactoring a Long Function

Compare these two examples:

// Long and complex function
function processUserData(user) {
  if (user.name) {
    user.name = user.name.trim();
  }
  if (user.email) {
    user.email = user.email.toLowerCase();
  }
  // ...
  return user;
}

// Refactored into smaller functions
function trimName(user) {
  if (user.name) {
    user.name = user.name.trim();
  }
  return user;
}

function normalizeEmail(user) {
  if (user.email) {
    user.email = user.email.toLowerCase();
  }
  return user;
}

In the first example, the processUserData function is long and complex, performing multiple tasks. In the second example, we've refactored the function into smaller, single-responsibility functions, making the code more efficient and readable.

Sample 2: Using Early Returns

Compare these two examples:

// Nested if-else statements
function isValidUser(user) {
  if (user.name) {
    if (user.email) {
      if (user.password) {
        return true;
      }
    }
  }
  return false;
}

// Using early returns
function isValidUser(user) {
  if (!user.name) return false;
  if (!user.email) return false;
  if (!user.password) return false;
  return true;
}

In the first example, the isValidUser function uses nested if-else statements, making the code hard to read. In the second example, we've used early returns to simplify the function and reduce nesting.

Sample 3: Simplifying a Function with Many Parameters

Compare these two examples:

// Function with many parameters
function createUser(name, email, password, role, isActive) {
  // ...
}

// Simplified function with an options object
function createUser(options) {
  const { name, email, password, role, isActive } = options;
  // ...
}

In the first example, the createUser function has many parameters, making it hard to understand and use. In the second example, we've simplified the function by using an options object, making the code more readable and maintainable.

By following best practices like single responsibility, short length, clear naming, minimal parameters, and early returns, you’ll write efficient, readable, and maintainable code.

Clean coding best practice 4 — Use error handling and logging

Error handling and logging are crucial aspects of Node.js development, ensuring your applications are robust, debuggable, and user-friendly. Without proper error handling and logging, your application may crash, lose data, or provide a poor user experience.

Error handling and logging offer several benefits, such as:

Robustness: Error handling ensures your application can recover from errors, reducing crashes and downtime.
Debugging: Logging helps you identify and debug issues, reducing development time and improving code quality.
User experience: Error handling provides a better user experience by catching and handling errors gracefully.
Security: Logging helps detect and respond to security incidents, protecting your application and users.

Error Handling Strategies

Node.js provides several error handling strategies:

Try-catch blocks: Catch and handle errors using try-catch blocks.
Error-first callbacks: Use error-first callbacks to handle errors in asynchronous code.
Promises: Use promises to handle errors in asynchronous code.
Async/await: Use async/await to handle errors in asynchronous code.

Logging Best Practices

Logging best practices include:

Use a logging library: Use a logging library like Winston, Morgan, or Pino to standardize logging.
Log errors and exceptions: Log errors and exceptions to identify and debug issues.
Log important events: Log important events, like user interactions or system events.
Use log levels: Use log levels (e.g., debug, info, warn, error) to categorize logs.

Sample 1: Try-Catch Block

Compare these two examples:

// Without try-catch block
function divide(a, b) {
  return a / b;
}

// With try-catch block
function divide(a, b) {
  try {
    return a / b;
  } catch (err) {
    console.error(err);
    return null;
  }
}

In the first example, the divide function doesn't handle errors, potentially causing a crash. In the second example, we've added a try-catch block to handle errors gracefully.

Sample 2: Error-First Callback

Compare these two examples:

// Without error-first callback
function getUserData(callback) {
  // ...
}

// With error-first callback
function getUserData(callback) {
  // ...
  callback(err, userData);
}

In the first example, the getUserData function doesn't handle errors, potentially causing a crash. In the second example, we've added an error-first callback to handle errors gracefully.

Sample 3: Logging with Winston

Compare these two examples:

// Without logging
function login(username, password) {
  // ...
}

// With logging using Winston
const winston = require('winston');
function login(username, password) {
  winston.info(`Login attempt by ${username}`);
  // ...
}

In the first example, the login function doesn't log important events, making debugging harder. In the second example, we've added logging using Winston to track important events.

Clean coding best practice 5 — Follow the DRY principle

The DRY (Don’t Repeat Yourself) principle is a fundamental concept in software development, and Node.js is no exception. The DRY principle aims to reduce repetition in code, making it more maintainable, efficient, and scalable.

Following the DRY principle offers several benefits:

Maintainability: Reduced repetition makes code easier to maintain and update.
Efficiency: Less code means less execution time and memory usage.
Readability: Concise code is easier to read and understand.
Reusability: DRY code promotes modular, reusable code.

DRY Principle Strategies

To follow the DRY principle, use these strategies:

Extract functions: Break down repetitive code into reusable functions.
Use loops and arrays: Replace repetitive code with loops and arrays.
Use template literals: Simplify repetitive string concatenation with template literals.
Use modules and imports: Reuse code by importing modules and functions.

Sample 1: Extracting Functions

Compare these two examples:

// Repetitive code
function processUserData(user) {
  if (user.name) {
    user.name = user.name.trim();
  }
  if (user.email) {
    user.email = user.email.toLowerCase();
  }
  // ...
}

// Extracted function
function trimAndNormalize(user) {
  if (user.name) {
    user.name = user.name.trim();
  }
  if (user.email) {
    user.email = user.email.toLowerCase();
  }
  return user;
}

function processUserData(user) {
  return trimAndNormalize(user);
}

In the first example, the processUserData function has repetitive code. In the second example, we've extracted the repetitive code into a reusable trimAndNormalize function.

Sample 2: Using Loops and Arrays

Compare these two examples:

// Repetitive code
function processArray(arr) {
  arr[0] = arr[0].toUpperCase();
  arr[1] = arr[1].toUpperCase();
  arr[2] = arr[2].toUpperCase();
  // ...
}

// Using loops and arrays
function processArray(arr) {
  return arr.map(item => item.toUpperCase());
}

In the first example, the processArray function has repetitive code. In the second example, we've replaced the repetitive code with a loop using the map method.

Sample 3: Using Template Literals

Compare these two examples:

// Repetitive string concatenation
function generateMessage(name, age) {
  return 'Hello, ' + name + '! You are ' + age + ' years old.';
}

// Using template literals
function generateMessage(name, age) {
  return `Hello, ${name}! You are ${age} years old.`;
}

In the first example, the generateMessage function has repetitive string concatenation. In the second example, we've simplified the code using template literals.

Let’s recall what we’ve learn in this article. To write clean and efficient Node.js code, follow these five best practices:

Modularize your code by breaking it down into smaller, independent modules that can be easily reused and maintained.
Use consistent naming conventions throughout your code to make it easy to read and understand.
Write clean and concise functions that have a single responsibility, are short and focused, and use early returns to reduce nesting.
Use error handling and logging to catch and handle errors gracefully, and to identify and debug issues quickly.
Follow the DRY (Don’t Repeat Yourself) principle by extracting functions, using loops and arrays, template literals, and modules and imports to reduce repetition.

Thanks for reading!

Five clean coding best practices in Node.js

Clean coding best practice 1 — Modularize your code

Clean coding best practice 2 — Use consistent naming conventions

Clean coding best practice 3 — Write clean and concise functions

Clean coding best practice 4 — Use error handling and logging

Clean coding best practice 5 — Follow the DRY principle

Written by Mayank C