Is there any way to list types of interface's properties?

Question

interface Inter {
    a: number;
    b: string;
}

let variable:(blabla);
             => right here.

I want to set the above to (number | string) using Inter's properties. Is there any way to do this? Thanks for reading !

Answer 1

You can use a type query with a type that is a union of all keys, which you can get keyof:

let val: Inter[keyof Inter]; // will be string | number

Answer 2

try:

let val: typeon Inter.a | val: typeon Inter.b