At first glance, you might write something like this:

const setA = new Set([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
const setB = new Set([2, 4, 6, 8, 10]);

function isSubset(setA, setB) {
  for (let elem of setB) {
    if (!setA.has(elem)) {
      return false;
    }
  }
  return true;
}

console.log(isSubset(setA, setB)); // Output: true

But recently, the Set object got upgraded with some new methods including a method called isSubsetOf which allows us to write something like this:

const setA = new Set([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
const setB = new Set([2, 4, 6, 8, 10]);

console.log(setB.isSubsetOf(setA)); // Output: true