Why is never assignable to every type?

Question

The TypeScript documentation says that

The never type is a subtype of, and assignable to, every type

but doesn\'t m

Answer 1

You are not calling the useNever function. If you try to call it with a parameter it will fail since a value can not be never. But as always, you can trick the compiler with typeguards e.g. this will work

const test = (val: string | number) => {
     if (typeof val === "string") {

     } else if (typeof val === "number") {

     } else {
         useNever(val); // works, since val is not number or string it is implicitly never
     }
 }