Reverse an Array in place. Note: No need to swap middle element if there is an off number of elements.

reverseArray.js

const reverseArray = arr => {
  const len = arr.length;
  const halfLen = Math.floor(len / 2);
  for (let i = 0; i < halfLen; i++) {
    const temp = arr[i];
    arr[i] = arr[len - i - 1];
    arr[len - i - 1] = temp;
  }
  return arr;
};