⚡ Best Practices for Web Developers

📝 Naming Conventions

JavaScript/TypeScript:

• camelCase for variables and functions: getUserData(), totalPrice
• PascalCase for classes and components: UserProfile, ProductCard
• CONSTANT_CASE for constants: MAX_RETRY_COUNT, API_BASE_URL
• Meaningful names: fetchUserOrders() not getUserStuff()

CSS:

• kebab-case for classes: .nav-link, .product-card
• BEM methodology: .block__element--modifier
• Descriptive names: .primary-button not .btn1

Files & Folders:

• kebab-case for files: user-profile.js, product-detail.html
• Lowercase folder names: components/, utils/, assets/

🧹 Clean Code Principles

• DRY (Don't Repeat Yourself): Extract repeated code into functions/components
• KISS (Keep It Simple, Stupid): Simple solutions over clever complexity
• YAGNI (You Aren't Gonna Need It): Don't build features you don't need yet
• Single Responsibility: Each function/component does one thing well
• Meaningful Names: Code should be self-documenting
• Comments: Explain WHY, not WHAT (code shows what)
• Consistent Formatting: Use linters (ESLint, Prettier)

🎯 Function Best Practices

✅ Good:

// Pure function, single responsibility, clear name
function calculateTotalPrice(items, taxRate) {
  const subtotal = items.reduce((sum, item) => sum + item.price, 0);
  return subtotal * (1 + taxRate);
}

❌ Bad:

// Does too much, unclear name, side effects
function doStuff(items) {
  let t = 0;
  for (let i = 0; i < items.length; i++) {
    t += items[i].price;
    console.log(items[i]); // side effect
  }
  return t * 1.08; // magic number
}

🔒 Never Trust User Input

Input Validation:

// ✅ Good: Validate and sanitize
function processEmail(email) {
  // Validate format
  const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
  if (!emailRegex.test(email)) {
    throw new Error('Invalid email format');
  }
  
  // Sanitize
  const sanitized = email.trim().toLowerCase();
  
  return sanitized;
}

Prevent XSS Attacks:

// ❌ NEVER do this (XSS vulnerability)
element.innerHTML = userInput;

// ✅ Use textContent or sanitize
element.textContent = userInput;

// ✅ Or use DOMPurify library
element.innerHTML = DOMPurify.sanitize(userInput);

🔐 Sensitive Data Handling

• ❌ Never hardcode API keys, passwords, or secrets in code
• ✅ Use environment variables (process.env.API_KEY)
• ❌ Never log sensitive data to console
• ❌ Never commit .env files to version control
• ✅ Add .env to .gitignore
• ✅ Use secrets management (AWS Secrets Manager, Azure Key Vault)
• ✅ Hash passwords with bcrypt/Argon2, never store plain text
• ✅ Always use HTTPS for transmitting sensitive data

⚡ Frontend Performance

Image Optimization:

• Use modern formats (WebP, AVIF) with fallbacks
• Compress images (80-85% quality sufficient)
• Use responsive images with srcset
• Lazy load below-the-fold images
• Use CDN for static assets

Code Optimization:

• Minify CSS, JavaScript, HTML for production
• Remove unused CSS (PurgeCSS)
• Code splitting (load only what's needed)
• Tree shaking (remove dead code)
• Use compression (gzip, Brotli)

Loading Performance:

• Minimize HTTP requests (bundle assets)
• Use browser caching headers
• Defer non-critical JavaScript
• Inline critical CSS
• Use preload for critical resources

📊 Measuring Performance

Core Web Vitals (Google Ranking Factors):

• LCP (Largest Contentful Paint): < 2.5s (page load speed)
• FID (First Input Delay): < 100ms (interactivity)
• CLS (Cumulative Layout Shift): < 0.1 (visual stability)

Tools:

• Google PageSpeed Insights
• Lighthouse (Chrome DevTools)
• WebPageTest
• Chrome DevTools Performance tab

♿ WCAG 2.1 Compliance

Semantic HTML:

<!-- ❌ Bad -->
<div onclick="submitForm()">Submit</div>

<!-- ✅ Good -->
<button type="submit">Submit</button>

Alt Text for Images:

<!-- ❌ Bad -->
<img src="product.jpg">

<!-- ✅ Good -->
<img src="product.jpg" alt="Blue running shoes with white sole">

ARIA Labels:

<nav aria-label="Main navigation">
  <button aria-label="Close dialog" aria-expanded="false">
    <span aria-hidden="true">×</span>
  </button>
</nav>

Keyboard Navigation:

• All interactive elements accessible via Tab key
• Visible focus indicators
• Skip to main content link
• Logical tab order
• Escape key closes modals/dropdowns

🌐 RESTful API Standards

HTTP Methods:

• GET - Retrieve data (idempotent, no side effects)
• POST - Create new resource
• PUT - Update entire resource
• PATCH - Partial update
• DELETE - Remove resource

Status Codes:

• 200 OK - Successful GET, PUT, PATCH, DELETE
• 201 Created - Successful POST
• 204 No Content - Successful DELETE with no response body
• 400 Bad Request - Invalid client request
• 401 Unauthorized - Authentication required
• 403 Forbidden - Authenticated but not authorized
• 404 Not Found - Resource doesn't exist
• 500 Internal Server Error - Server error

Endpoint Naming:

✅ Good: RESTful, plural nouns
GET    /api/users
GET    /api/users/123
POST   /api/users
PUT    /api/users/123
DELETE /api/users/123

❌ Bad: Verbs in URLs, inconsistent
GET /api/getUsers
POST /api/createUser
GET /api/user/123

📦 Git Workflow

Commit Messages:

✅ Good: Clear, descriptive, imperative mood
feat: Add user authentication with JWT
fix: Resolve mobile navigation overflow bug
docs: Update API documentation for v2.0
refactor: Extract validation logic into utils

❌ Bad: Vague, unclear
updated stuff
fix bug
changes
wip

Branching Strategy:

• main - Production-ready code
• develop - Integration branch for features
• feature/feature-name - New features
• bugfix/bug-description - Bug fixes
• hotfix/critical-fix - Emergency production fixes

.gitignore Essentials:

node_modules/
.env
.env.local
dist/
build/
*.log
.DS_Store
.vscode/

🧪 Testing Strategy

Test Pyramid:

• 70% Unit Tests: Test individual functions/components
• 20% Integration Tests: Test component interactions
• 10% E2E Tests: Test full user workflows

What to Test:

• ✅ Business logic and calculations
• ✅ Edge cases and error handling
• ✅ User interactions and form validation
• ✅ API integrations
• ❌ Don't test framework internals
• ❌ Don't test third-party libraries

📖 Code Documentation

README.md Should Include:

• Project description and purpose
• Installation instructions
• Usage examples
• Configuration options
• API documentation or link
• Contributing guidelines
• License information

Code Comments:

// ✅ Good: Explain WHY, not WHAT
// Using setTimeout to debounce rapid API calls
// Prevents rate limit errors from search-as-you-type
setTimeout(() => fetchResults(query), 300);

// ❌ Bad: Stating the obvious
// Set timeout to 300
setTimeout(() => fetchResults(query), 300);

🚀 Production Checklist

• ☐ Environment variables configured
• ☐ HTTPS enabled with valid SSL certificate
• ☐ Assets minified and compressed
• ☐ Error logging configured (Sentry, LogRocket)
• ☐ Database backups automated
• ☐ Security headers configured
• ☐ Rate limiting implemented
• ☐ CDN configured for static assets
• ☐ Monitoring and alerts set up
• ☐ Rollback plan documented
• ☐ Performance tested under load
• ☐ Accessibility tested (WCAG 2.1 AA)
• ☐ Cross-browser testing completed
• ☐ Mobile responsiveness verified
• ☐ SEO meta tags configured