Clean Code JavaScript – Function Patterns

Table of Contents

• Single Responsibility
• Function Size
• Parameters
• Side Effects

Single Responsibility

// ❌ Bad
function handleUser(user) {
  saveUser(user);
  sendEmail(user);
}

// ✅ Good
function saveUser(user) {}
function notifyUser(user) {}

Function Size

Keep functions small (ideally < 20 lines).

Parameters

// ❌ Bad
function createUser(name, age, city, zip) {}

// ✅ Good
function createUser({ name, age, address }) {}

Side Effects

// ❌ Bad
let total = 0;
function add(value) {
  total += value;
}

// ✅ Good
function add(total, value) {
  return total + value;
}