isSubsetOf < Set < JavaScript

New, not-widely-supported method 1/24. The isSubsetOf() method of a Set takes a set and returns a boolean indicating if all elements of this set are in the given set.

    
    const fours = new Set([4, 8, 12, 16]);

    const evens = new Set([2, 4, 6, 8, 10, 12, 14, 16, 18]);

    const foursSubsetOfEvens = fours.isSubsetOf(evens);

    console.log(foursSubsetOfEvens);
    // true