JS Practice — Built-in Objects

Type Guard — isObject

📖 Usage Example

function isObject(x: unknown): x is Record<string, unknown> {
  return typeof x === 'object' && x !== null
}
isObject({})     // → true
isObject(null)   // → false

A proper isObject guard checks typeof === 'object' AND x !== null, since typeof null is 'object'.

Type Guards: isObject

Challenge: Implement isObject(x: unknown): x is Record<string, unknown>.
Arrays and null should return false.

isObject({})     // → true
isObject([])     // → false  (arrays are not plain objects)
isObject(null)   // → false  (typeof null === 'object' — a classic JS gotcha)

💡 Hints (1)

• Check typeof, exclude null, exclude arrays.