Generics Introduction

Intermediate~20 min

Generics allow you to write reusable code that works with multiple types while maintaining type safety.

What Are Generics?

Output

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Generic Syntax: Use angle brackets <T> to define type parameters. T is a placeholder for any type.

Why Use Generics?

Reusability: Write once, use with any type
Type safety: Catch errors at compile-time
No type casting: TypeScript infers types
Better IDE support: Autocomplete works perfectly

Generics vs Any

Feature	Generics	Any
Type safety	✓ Full type checking	✗ No type checking
Autocomplete	✓ Works perfectly	✗ No autocomplete
Refactoring	✓ Safe refactoring	✗ Unsafe
Return type	✓ Preserves type	✗ Returns any

Common Mistakes

1. Using Any Instead of Generics

// ✗ Wrong - loses type safety
function identity(value: any): any {
    return value;
}

// ✓ Correct - maintains type safety
function identity(value: T): T {
    return value;
}

2. Not Specifying Type Parameters

// Works but less explicit
let result = identity(42);  // Type inferred

// ✓ Better - explicit type
let result = identity(42);

Best Practice: Use generics when you need type-safe reusable code. Common naming: T (Type), K (Key), V (Value).

Summary

Generics enable reusable, type-safe code
Use <T> syntax for type parameters
Better than any - preserves type information
TypeScript can infer generic types

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