intersection-of-arrays.js

function intersection(array1, array2) {
  const intersectionOfArrays = [];
  const cache = {};
  array1.forEach(element => {
    cache[element] = element; /// filling up my dictionary
  });
  array2.forEach(element => {
    if (cache[element]) {
      intersectionOfArrays.push(element);
    }
  });
  return intersectionOfArrays;
}

const array1 = [1, 3, 5, 2];
const array2 = [4, 6, 5, 3];

const result = intersection(array1, array2);

console.log(result);