JS Built-ins
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ArrayArray.prototype.atbeginner

Array.prototype.at() — second-to-last element

📖 Usage Example
const items = ['a', 'b', 'c', 'd']
items.at(-2)  // → 'c'
items.at(-1)  // → 'd'

Use at() with negative indices to access elements from the end of an array.

Array.prototype.at() — counting from the end

.at(-2) gives you the second-to-last element. Compare this to the bracket notation equivalent: arr[arr.length - 2] — .at() is much more readable.

Challenge: Implement getSecondToLast(arr) that returns the second-to-last element using .at(-2).

getSecondToLast([1, 2, 3, 4]) // → 3
getSecondToLast(['a', 'b'])   // → 'a'
💡 Hints (2)
  • • `arr.at(-2)` counts 2 from the end, equivalent to `arr[arr.length - 2]`.
  • • If the array has fewer than 2 elements, `.at(-2)` returns `undefined`.