Arbitrary arrays in JavaScript

Multidimensional arrays do not have to be the same as we discussed above. Look at the following array for example:

javascriptlet arr = [['a', 'b', [1, 2, 3], [4, 5]], ['d', ['e', 'f']]];

As you can see, this array is "unusual". It contains arrays ([1, 2, 3] and ⁅ c⁆[4, 5]) next to regular elements (for example, 'a', 'b'). Let's rewrite our array in a more understandable way:

javascriptlet arr = [
  [
    'a', 'b', [1, 2, 3], [4, 5],
  ],
  [
    'd', ['e', 'f'],
  ],
];

javascriptlet arr = [[1, 2, 3, [4, 5, [6, 7]]], [8, [9, 10]]];