Typescript find type of union type

Question

I want to know the type c in printTypeOf function. Here is my code:

type Email ={
    email:string,
}
type Phone ={
    phone:string,
}
type ContactInfo = Email | Phone;

function printTypeOf(c: ContactInfo) {
    console.log(typeof c)
}

const x: Email = { email: "X" };
printTypeOf(x);

Current output is object but I need to find if it is Email or Phone

Answer 1

You can't print a name of a type because once TypeScript is transpiled to JavaScript all the type information is lost. It prints object because that's what the TypeScript turns into once you have running code.