Union and Intersection in Javascript Array in ES6

By using Set in ES6 easily we can achieve

public union(setA, setB) {

let _union = new Set(setA);

for (var elem of setB) {

_union.add(elem);

}

return _union;

}

public intersection(setA, setB) {

let _intersection = new Set();

for (let elem of setB) {

if (setA.has(elem)) {

_intersection.add(elem);

}

}

return _intersection;

}