function intersetSet(SetA,SetB){
  let intersection =new Set();
  for(var elem of SetB) {
    if(SetA.has(elem)) {
      intersection.add(elem);
    }
    return intersection;
  }
}
let SetA = new Set([1,2,3,4]),
SetB = new Set([2,3]);

console.log(intersetSet(SetA,SetB))