typeof type operator in Typescript

Javascript has a typeof operator that you can use in an expression context. Typescript adds a typeof operator that you can use in a type context to refer to the type of a variable or property.

function f() {
  return { x: 10, y: 3 };
}
type P = ReturnType<typeof f>;
//   ^ = type P = {
//       x: number;
//       y: number;
//   }

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