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Clean Code

Clean Code

Introduction

Clean code is code that is easy to read, understand, and maintain. It’s the most important skill for professional developers.

Naming

// ❌ Bad
function d(a, b) { return a - b; }
const x = ['Alice', 'Bob'];

// ✅ Good
function calculateDifference(a, b) { return a - b; }
const userNames = ['Alice', 'Bob'];

Functions

// ❌ Bad — too many responsibilities
function processUser(user) {
  // validate
  // save to DB
  // send email
  // log
}

// ✅ Good — single responsibility
function validateUser(user) { /* ... */ }
function saveUser(user) { /* ... */ }
function sendWelcomeEmail(user) { /* ... */ }

Avoid Deep Nesting

// ❌ Bad
function process(order) {
  if (order) {
    if (order.isValid) {
      if (order.paid) {
        // process
      }
    }
  }
}

// ✅ Good — guard clauses
function process(order) {
  if (!order) return;
  if (!order.isValid) return;
  if (!order.paid) return;
  // process
}

Summary

Meaningful names for variables and functions
Functions should do one thing (single responsibility)
Use guard clauses to reduce nesting
Keep functions small (under 20 lines ideally)
Comments explain WHY, not WHAT

Further Reading

Clean Code: JavaScript