The keys() method of Set instances is an alias for the values() method.
Syntax
keys()
Parameters
None.
Return value
A new iterable iterator object.
Examples
Using keys()
The keys() method is exactly equivalent to the values() method.
const mySet = new Set();
mySet.add("foo");
mySet.add("bar");
mySet.add("baz");
const setIter = mySet.keys();
console.log(setIter.next().value); // "foo"
console.log(setIter.next().value); // "bar"
console.log(setIter.next().value); // "baz"