JS Practice — Built-in Objects

Type Guard — safe access

📖 Usage Example

function safeGet<T>(obj: T | null | undefined, key: keyof NonNullable<T>) {
  return obj?.[key as keyof typeof obj]
}
// Returns undefined safely when obj is null or undefined

Optional chaining (?.) safely accesses properties on potentially nullish values without throwing.

Type Guards: Safe Property Access

Challenge: Implement safeGet<T, K extends keyof T>(obj: T | null | undefined, key: K): T[K] | undefined — returning the property value if obj exists, or undefined otherwise.

safeGet({ name: 'Alice' }, 'name')  // → 'Alice'
safeGet(null, 'name')               // → undefined

💡 Hints (1)

• obj != null is true when obj is neither null nor undefined (loose inequality).