Coding Standards & Best Practices

Universal coding standards applicable across all projects.

Methodology Integration

These standards complement the principles in .claude/docs/APPROACH.md:

•Small, verifiable steps
•Interface-first development
•Documentation as memory

Code Quality Principles

1. Readability First

•Code is read more than written
•Clear variable and function names
•Self-documenting code preferred over comments
•Consistent formatting

2. KISS (Keep It Simple)

•Simplest solution that works
•Avoid over-engineering
•No premature optimization
•Easy to understand > clever code

3. DRY (Don't Repeat Yourself)

•Extract common logic into functions
•Create reusable components
•Share utilities across modules
•Avoid copy-paste programming

4. YAGNI (You Aren't Gonna Need It)

•Don't build features before they're needed
•Avoid speculative generality
•Add complexity only when required
•Start simple, refactor when needed

TypeScript/JavaScript Standards

Variable Naming

typescript

// GOOD: Descriptive names
const searchQuery = 'election'
const isUserAuthenticated = true
const totalRevenue = 1000

// BAD: Unclear names
const q = 'election'
const flag = true
const x = 1000

Function Naming

typescript

// GOOD: Verb-noun pattern
async function fetchMarketData(marketId: string) { }
function calculateSimilarity(a: number[], b: number[]) { }
function isValidEmail(email: string): boolean { }

// BAD: Unclear or noun-only
async function market(id: string) { }
function similarity(a, b) { }

Immutability Pattern (CRITICAL)

typescript

// ALWAYS use spread operator
const updatedUser = {
  ...user,
  name: 'New Name'
}

const updatedArray = [...items, newItem]

// NEVER mutate directly
user.name = 'New Name'  // BAD
items.push(newItem)     // BAD

Error Handling

typescript

// GOOD: Comprehensive error handling
async function fetchData(url: string) {
  try {
    const response = await fetch(url)

    if (!response.ok) {
      throw new Error(`HTTP ${response.status}: ${response.statusText}`)
    }

    return await response.json()
  } catch (error) {
    console.error('Fetch failed:', error)
    throw new Error('Failed to fetch data')
  }
}

Async/Await Best Practices

typescript

// GOOD: Parallel execution when possible
const [users, markets, stats] = await Promise.all([
  fetchUsers(),
  fetchMarkets(),
  fetchStats()
])

// BAD: Sequential when unnecessary
const users = await fetchUsers()
const markets = await fetchMarkets()
const stats = await fetchStats()

Type Safety

typescript

// GOOD: Proper types
interface Market {
  id: string
  name: string
  status: 'active' | 'resolved' | 'closed'
  created_at: Date
}

function getMarket(id: string): Promise<Market> {
  // Implementation
}

// BAD: Using 'any'
function getMarket(id: any): Promise<any> {
  // Implementation
}

React Best Practices

Component Structure

typescript

// GOOD: Functional component with types
interface ButtonProps {
  children: React.ReactNode
  onClick: () => void
  disabled?: boolean
  variant?: 'primary' | 'secondary'
}

export function Button({
  children,
  onClick,
  disabled = false,
  variant = 'primary'
}: ButtonProps) {
  return (
    <button
      onClick={onClick}
      disabled={disabled}
      className={`btn btn-${variant}`}
    >
      {children}
    </button>
  )
}

State Management

typescript

// GOOD: Proper state updates
const [count, setCount] = useState(0)

// Functional update for state based on previous state
setCount(prev => prev + 1)

// BAD: Direct state reference
setCount(count + 1)  // Can be stale in async scenarios

API Design Standards

REST API Conventions

code

GET    /api/resources              # List resources
GET    /api/resources/:id          # Get single resource
POST   /api/resources              # Create resource
PUT    /api/resources/:id          # Replace resource
PATCH  /api/resources/:id          # Update resource
DELETE /api/resources/:id          # Delete resource

Response Format

typescript

interface ApiResponse<T> {
  success: boolean
  data?: T
  error?: string
  meta?: {
    total: number
    page: number
    limit: number
  }
}

Input Validation

typescript

import { z } from 'zod'

const CreateResourceSchema = z.object({
  name: z.string().min(1).max(200),
  description: z.string().min(1).max(2000),
})

export async function POST(request: Request) {
  const body = await request.json()

  try {
    const validated = CreateResourceSchema.parse(body)
    // Proceed with validated data
  } catch (error) {
    if (error instanceof z.ZodError) {
      return NextResponse.json({
        success: false,
        error: 'Validation failed',
        details: error.errors
      }, { status: 400 })
    }
  }
}

File Organization

File Naming

code

components/Button.tsx          # PascalCase for components
hooks/useAuth.ts              # camelCase with 'use' prefix
lib/formatDate.ts             # camelCase for utilities
types/market.types.ts         # camelCase with .types suffix

Comments & Documentation

When to Comment

typescript

// GOOD: Explain WHY, not WHAT
// Use exponential backoff to avoid overwhelming the API during outages
const delay = Math.min(1000 * Math.pow(2, retryCount), 30000)

// BAD: Stating the obvious
// Increment counter by 1
count++

Code Smell Detection

Watch for these anti-patterns:

Long Functions (>50 lines)

Split into smaller functions with single responsibilities.

Deep Nesting (>4 levels)

Use early returns to flatten.

Magic Numbers

Use named constants.

Remember: Code quality is not negotiable. Clear, maintainable code enables rapid development and confident refactoring.