JS Practice — Built-in Objects

unshift Mutates the Array

📖 Usage Example

const arr = ['b', 'c']
arr.unshift('a')
console.log(arr)  // → ['a', 'b', 'c']  (mutated)

unshift() mutates the original array — use toSpliced(0, 0, el) for an immutable alternative.

Array.prototype.unshift — Mutation

unshift modifies the original array in place. After calling it, the prepended value becomes arr[0].

Implement prependAndCheck which unshifts val and returns arr[0] to confirm it is now the first element.

💡 Hints (2)