What Are Generics in TypeScript?

Generics in TypeScript are a way to create reusable, flexible, and type-safe code components—like functions, interfaces, or classes—that can work with different types without losing the benefits of type checking.

Instead of hardcoding a type, you use a type variable that gets replaced with a specific type when the code is used.

📦 Why Use Generics?

Without generics, you might write:

❌ Problem: You lose type safety. The return type is always any.

✅ With generics:

You get:

• Type inference

• Auto-completion

• Compile-time safety

🧪 Generic Syntax Basics

• T is a generic type parameter

• It can be any valid identifier (like T, U, K, V)

• You can have multiple type parameters

🧰 Generics in Different Contexts

✅ 1. Functions

✅ 2. Interfaces

✅ 3. Classes

✅ 4. Constraints with extends

You can limit what types are allowed:

✅ 5. Default Generic Types

✅ 6. Using keyof with Generics

🎯 When to Use Generics

Use generics when:

• You want to write type-safe, reusable code

• Your function/component works with multiple types

• You want to retain type information across inputs and outputs

🚫 When Not to Use Generics

Avoid generics when:

• The type is known and fixed

• The logic is too specific to a single type

• It adds unnecessary complexity