What does the following ‘const’ type parameter (TypeScript 5.0) infer? function identity(value: T): T { return value; } const result = identity({ x: 1, y: ‘hello’ });

Question

TypeScript Professional — Hard

What does the following ‘const’ type parameter (TypeScript 5.0) infer? function identity(value: T): T { return value; } const result = identity({ x: 1, y: ‘hello’ });

Accepted Answer

The 'const' type parameter in TypeScript 5.0 infers { readonly x: 1; readonly y: 'hello' } for the given function. This is because const inference produces narrow literal types with readonly modifiers, ensuring immutability.