// not working yet
function intersection(a, b) {
  const ints = [];
  for (let i = 0, al = a.length, bl = b.length; i < al; ++i) {
    if (b.includes(a[i]) && ints.length < bl) {
      ints.push(a[i]);
    }
  }
  return ints;//a.filter((x => b.includes(x));
}

console.clear();

console.log(`===================================`);
var x = [1,2,2,1], y = [2,2];
console.log(x, y);
console.log('FINAL ===>', intersection(x,y)); //[2,2]

var x = [4,9,5], y = [9,4,9,8,4];
console.log(x, y);
console.log('FINAL ===>', intersection(x,y));// [4,9]

var x = [1,2,2,1], y = [2];
console.log(x, y);
console.log('FINAL ===>', intersection(x,y));// [2]

var x = [61,24,20,58,95,53,17,32,45,85,70,20,83,62,35,89,5,95,12,86,58,77,30,64,46,13,5,92,67,40,20,38,31,18,89,85,7,30,67,34,62,35,47,98,3,41,53,26,66,40,54,44,57,46,70,60,4,63,82,42,65,59,17,98,29,72,1,96,82,66,98,6,92,31,43,81,88,60,10,55,66,82,0,79,11,81];
var y = [5,25,4,39,57,49,93,79,7,8,49,89,2,7,73,88,45,15,34,92,84,38,85,34,16,6,99,0,2,36,68,52,73,50,77,44,61,48];
var x = [1,2,2,1], y = [2];
console.log(x, y);
console.log('FINAL ===>', intersection(x,y));// [5,4,57,79,7,89,88,45,34,92,38,85,6,0,77,44,61]