offset

Moves the specified amount of elements to the end of the array.

• Use Array.prototype.slice() twice to get the elements after the specified index and the elements before that.
• Use the spread operator (...) to combine the two into one array.
• If offset is negative, the elements will be moved from end to start.

const offset = (arr, offset) => [...arr.slice(offset), ...arr.slice(0, offset)];

offset([1, 2, 3, 4, 5], 2); // [3, 4, 5, 1, 2]
offset([1, 2, 3, 4, 5], -2); // [4, 5, 1, 2, 3]