JS Practice — Built-in Objects

Array.isArray() — why not typeof

📖 Usage Example

typeof []          // → 'object'  (misleading)
Array.isArray([])  // → true      (accurate)

Prefer Array.isArray() over typeof for array detection — typeof returns 'object' for arrays.

Array.isArray() vs typeof

typeof [] returns 'object' — the same as for plain objects, null, and other non-primitives. Array.isArray() was introduced specifically to distinguish real arrays from objects.

Challenge: Implement isRealArray that returns true only for real arrays (not other objects) by using Array.isArray.

isRealArray([])           // → true  (typeof [] === 'object' too!)
isRealArray({})           // → false
isRealArray(null)         // → false (typeof null === 'object' — gotcha!)

💡 Hints (2)

• `typeof null === "object"` is a famous JavaScript quirk — always use `Array.isArray` for arrays.
• `typeof []` also returns `"object"`, making `typeof` useless for this check.