Typescript type guard for requiring all elements

Question

Is there a way to require array elements with typescript so that I can do have

type E = keyof T; // Number of properties in T is unknown

let T

Answer 1

You can create a tuple:

type E = "el1"|"el2"|"el3";

type ITestElement = {
    arg: T
};

type ITestElements = [ITestElement<"el1">, ITestElement<"el2">, ITestElement<"el3">];