JS Practice — Built-in Objects

Array.prototype.flat() — remove falsy and flat

📖 Usage Example

const holey = [1, , 3, , 5]
holey.flat()  // → [1, 3, 5]  (holes removed)

flat() removes empty slots from sparse arrays while flattening.

Array.prototype.flat() — combining with filter

flat() can be combined with filter to both remove unwanted values and flatten the result.

Challenge: Implement removeHoles(arr) that filters out falsy values then calls flat().

removeHoles([1, undefined, 2, null, 3]) // → [1, 2, 3]
removeHoles([0, [1, 2], undefined])     // → [1, 2]

💡 Hints (2)

• `filter(Boolean)` removes all falsy values.
• `.flat()` after filter ensures any nested arrays (not filtered) are also unwrapped.