clean-code

Clean Code Best Practices

Overview

Principle	Description
Readability	Code is read more than written
Simplicity	Simple is better than complex
Consistency	Follow established patterns
Testability	Write code that's easy to test

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Naming Conventions

Use Descriptive Names

// ❌ Bad - Unclear names
const d = new Date()
const u = getUser()
function calc(a, b) { return a + b }

// ✅ Good - Clear, descriptive names
const currentDate = new Date()
const authenticatedUser = getUser()
function calculateTotal(price, quantity) { return price * quantity }

Use Consistent Naming Patterns

// Boolean variables: is, has, should, can
const isActive = true
const hasPermission = user.role === 'admin'
const shouldRefresh = lastUpdate < Date.now() - 60000
const canEdit = hasPermission && isActive

// Functions: verb + noun
function getUser(id: string) {}
function createOrder(data: OrderData) {}
function validateEmail(email: string) {}
function calculateDiscount(price: number) {}

// Event handlers: handle + event
function handleClick() {}
function handleSubmit() {}
function handleUserCreated() {}

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Functions

Keep Functions Small and Focused

// ❌ Bad - Does too many things
function processOrder(order) {
  // Validate order
  if (!order.items) throw new Error('No items')
  if (!order.userId) throw new Error('No user')
  
  // Calculate total
  let total = 0
  for (const item of order.items) {
    total += item.price * item.quantity
  }
  
  // Apply discount
  if (order.coupon) {
    total *= 0.9
  }
  
  // Save to database
  db.orders.create({ ...order, total })
  
  // Send email
  sendEmail(order.userId, 'Order confirmed')
}

// ✅ Good - Single responsibility
function validateOrder(order: Order): void {
  if (!order.items?.length) throw new Error('Order must have items')
  if (!order.userId) throw new Error('Order must have userId')
}

function calculateOrderTotal(items: OrderItem[], coupon?: Coupon): number {
  const subtotal = items.reduce((sum, item) => sum + item.price * item.quantity, 0)
  return coupon ? applyDiscount(subtotal, coupon) : subtotal
}

function processOrder(order: Order): void {
  validateOrder(order)
  const total = calculateOrderTotal(order.items, order.coupon)
  saveOrder({ ...order, total })
  notifyUser(order.userId, 'Order confirmed')
}