What does the following TypeScript achieve? function assertNever(x: never): never { throw new Error(‘Unexpected value: ‘ + x); }

Question

TypeScript Associate — Hard

What does the following TypeScript achieve? function assertNever(x: never): never { throw new Error(‘Unexpected value: ‘ + x); }

Accepted Answer

The function assertNever in TypeScript enables exhaustive checking in switch/if-else chains. If a case is missed, TypeScript will report a compile-time error because x would not be never, ensuring all cases are handled.