TypeScript return type of typeof should be string?

Question

type typeof_returntype = ReturnType<typeof typeof> // should be string?

I was just playing around when I noticed that I can't get the return type of the function typeof. Is this by design?

Answer 1

typeof is an operator not a function, therefore one cannot extract its return type. But one can get "the union of string literal results of typeof as a type if you wrap the operator in a function".

const typeOf = (x: any) => typeof(x);
type typeof_returntype = ReturnType<typeof typeOf>;
// "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"

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Quote by @jcalz