code: function simpleIntersection(array1, array2) {
    return array1
      // Remove falsy elements
      .filter(el => el)
      // Match elements belonging in the two arrays
      .filter(el => array2.indexOf(el) !== -1)
      // Remove duplicates
      .filter((el, idx, arr) => arr.indexOf(el) === idx);
  }
docs: Simple truthy-only, unique intersection function of two arrays.
  
  @param Array   array1
  @param Array   array2
  
  @return Array