lalka

Babel + JSX

const arr1 = [1, 2, 5, 9],
      arr2 = [2, 5, 100, 0, 41];
      
function uniq(...input) {
  const results = new Map();
  for (const group of input) {
    for (const elem of group) {
      results.set(elem, (results.get(elem) || 0) + 1);
    }
  }
  let count = 0;
  for (const val of results.values()) {
    if (val == 1) count = count + 1;
  }
  return count;
}

alert(uniq(arr1, arr2));