const new = new Set(old);

const new = ...old

for (let value of set.values()) {
  ...
}

Array.from(new Set())

function setMath<T>(a: Set<T>, b: Set<T>) {
  return {
    remove: [...a].filter(x => !b.has(x)),
    add: [...b].filter(x => !a.has(x)),
  };
}