JS Practice — Built-in Objects

Object.hasOwn() — vs hasOwnProperty

📖 Usage Example

// Check if a property is directly on the object
const obj = { name: 'Alice' }
Object.hasOwn(obj, 'name')      // → true
Object.hasOwn(obj, 'toString')  // → false

Use Object.hasOwn() to reliably check if a property is an own property, without being fooled by inherited properties.

Object.hasOwn() — safer than hasOwnProperty

Object.prototype.hasOwnProperty can fail if the object has a property named hasOwnProperty or has no prototype. Object.hasOwn is always safe.

Challenge: Implement safeCheck(obj, key) that uses Object.hasOwn (not hasOwnProperty) to check ownership.

safeCheck({ a: 1 }, 'a') // → true

💡 Hints (1)

• `Object.hasOwn` works even on objects with no prototype (`Object.create(null)`) or with a shadowed `hasOwnProperty`.