Reverse an array in place

Write a function reverseInPlace(arr) that reverses an array in place: the first element changes places with the last one, the second with the one before the last, and so on.

• arr is an array of numbers or strings. It can be empty.
• Change arr itself (mutate it), do not build a new array.
• Return the same array arr, not a copy.
• Do not use the built-in reverse() or toReversed(), also not on a copy of the array. Hidden tests replace them with functions that throw an error.
• An empty array and an array of one element stay as they are.

Use two indexes: one from the start and one from the end. Swap the elements at each index pair and move the indexes toward each other.