nthElement

Returns the nth element of an array.

• Use Array.prototype.slice() to get an array containing the nth element at the first place.
• If the index is out of bounds, return undefined.
• Omit the second argument, n, to get the first element of the array.

const nthElement = (arr, n = 0) =>
  (n === -1 ? arr.slice(n) : arr.slice(n, n + 1))[0];

nthElement(['a', 'b', 'c'], 1); // 'b'
nthElement(['a', 'b', 'b'], -3); // 'a'