Array.prototype.at takes an integer value and returns the item at that index, allowing for positive and negative integers. Negative integers count back from the last item in the array.
Implement Array.prototype.at. To avoid overwriting the actual Array.prototype.at, we shall instead implement it as Array.prototype.myAt.
const arr = [42, 79];
arr.myAt(0);// 42
arr.myAt(1);// 79
arr.myAt(2);// undefined
arr.myAt(-1);// 79
arr.myAt(-2);// 42
arr.myAt(-3);// undefined
There are some tricky cases to handle. You are recommended to read the specification for Array.prototype.at on MDN Docs before attempting.