Write a JavaScript program to get the symmetric difference between two given arrays, after applying the provided function to each array element of both

const symmetricDifferenceBy = (a, b, fn) => {
  const sA = new Set(a.map(v => fn(v))),
    sB = new Set(b.map(v => fn(v)));
  return [...a.filter(x => !sB.has(fn(x))), ...b.filter(x => !sA.has(fn(x)))];
};
console.log(symmetricDifferenceBy([2.1, 1.2], [2.3, 3.4], Math.floor));