JavaScript & TypeScript

Best practices for JavaScript and TypeScript development.

When to Use

• Writing frontend or backend JavaScript/TypeScript code
• Setting up new Node.js or browser projects
• Code review and refactoring

TypeScript Guidelines

Strict Mode

Always enable strict mode in tsconfig.json:

{
  "compilerOptions": {
    "strict": true,
    "noImplicitAny": true,
    "strictNullChecks": true
  }
}

Type Best Practices

// Prefer interfaces for object shapes
interface User {
  id: string;
  name: string;
  email: string;
}

// Use union types for alternatives
type Status = 'idle' | 'loading' | 'success' | 'error';

// Prefer readonly for immutable data
class Config {
  readonly apiUrl: string;
}

JavaScript Patterns

Async/Await

// Prefer async/await over promise chains
async function fetchData(url) {
  const response = await fetch(url);
  return response.json();
}

Error Handling

try {
  await operation();
} catch (error) {
  logger.error('Operation failed', { error });
  throw error; // Re-throw or handle
}

Resources

• TypeScript Handbook
• MDN JavaScript Guide