These are the key best practices for building production-quality JavaScript applications.

• Use const by default, let when needed
• Always use === (strict equality)
• Use optional chaining ?. and nullish coalescing ??
• Prefer arrow functions for callbacks

• Lazy load images and components
• Use requestAnimationFrame for visual updates
• Debounce/throttle expensive event handlers
• Avoid layout thrashing (batch read/write)

• Never trust user input
• Use textContent not innerHTML for user data
• Implement Content Security Policy (CSP)
• Keep dependencies updated

• Write self-documenting code
• Keep functions small and focused
• Prefer composition over inheritance
• Write tests for critical paths

• Consistency is more important than perfection
• Follow project conventions
• Review code before merging
• Document architectural decisions

• JavaScript Best Practices