JS Practice — Built-in Objects

Array.prototype.splice() — insert an element

📖 Usage Example

const arr = [1, 2, 4, 5]
arr.splice(2, 0, 3)  // insert 3 at index 2
arr  // → [1, 2, 3, 4, 5]

Pass 0 as deleteCount and provide values to splice() to insert elements without removing any.

Array.prototype.splice() — inserting

Passing 0 as the deleteCount tells splice to delete nothing and only insert elements at the given position.

Challenge: Implement insertAt(arr, index, val) that inserts val at index (shifting existing elements right) and returns the mutated array.

insertAt([1, 2, 3], 1, 99) // → [1, 99, 2, 3]
insertAt([10, 20], 0, 5)   // → [5, 10, 20]

💡 Hints (2)