You Aren’t Gonna Need It

• Don’t write code unless it’s required now.
• Avoid solving problems that don’t yet exist.
• Focus on delivering the simplest solution for today.

why yagni matters

• save time
• reduce complexcity
• prevent overengineering
• encourage itrative development Eg.

// Overengineered:
interface User {
  id: number
  name: string
  address?: {
    street: string
    city: string
  }
}
// Keep it simple:
interface User {
  id: number
  name: string
}

when to break yagni

• Performance Requirements
• Future Scalability
• Security Requirements
• Error Handling in Critical Systems

If the cost of not doing it now outweighs doing it later, it might make sense to break YAGNI.

YAGNI Guidelines for Utility Libraries ✅ DO Build: Current Requirements Only Extension Points (Not Extensions) Hooks/callbacks for customization Composition over configuration Most common use case = zero config

Clear, Minimal API

Small surface area Each method has clear purpose