JS: Set.prototype.keys

(new in JS: ECMAScript 2015)

mySet.keys()

• Return a Generator.
• Each yield of the iterator is a element of the set.

console.log(
  JSON.stringify(Array.from(
    (new Set([3, 4])).keys(),
  )) === `[3,4]`,
);
// true

const xx = (new Set([3, 4])).keys();

// is a iterable
console.log(Reflect.has(xx, Symbol.iterator));
// true

// is a iterator
console.log(Reflect.has(xx, "next"));
// true