How to use map() on an array in reverse order with JavaScript?

To use map() on an array in reverse order with JavaScript, we make a copy before we reverse the array.

For instance, we write

myArray
  .slice(0)
  .reverse()
  .map((a) => {
    //...
  });

to call slice to make a copy of myArray and return it.

And then we call reverse to reverse the copied array.

Then we call map to map the entries of the reversed array.