enum Animals {
  CAT,
  DOG,
  PARROT,
  SHEEP,
  SALMON
}

The following type:

type AnimalsToMappedType = {
  [K in keyof typeof Animals]: K
}

Results in:

type AnimalsToMappedType = {
  readonly [x: number]: number;
  readonly CAT: "CAT";
  readonly DOG: "DOG";
  readonly PARROT: "PARROT";
  readonly SHEEP: "SHEEP";
  readonly SALMON: "SALMON";
}

But if you add parenthesis around keyof typeof Animals:

type AnimalsToMappedType = {
  [K in (keyof typeof Animals)]: K
}

The result is:

type AnimalsToMappedType = {
    CAT: "CAT";
    DOG: "DOG";
    PARROT: "PARROT";
    SHEEP: "SHEEP";
    SALMON: "SALMON";
}

QUESTION

What are the parenthesis doing that removes readonly [x: number]: number;?