Javascript Set is super set

function isSuperset (setA, subset) {
    for (var elem of subset) {
        if (!setA.has(elem)) {
            return false;
        }//w w  w .  ja v a2 s .  c  o m
    }
    return true;
}

var setA = new Set([1, 2, 3, 4]),
    setB = new Set([2, 3]),
    setC = new Set([5]);

let a = isSuperset(setA, setB); 
console.log(a);