JS Practice — Built-in Objects

Object.isSealed() — after Object.freeze

📖 Usage Example

// Check if an object is sealed
const obj = { a: 1 }
Object.isSealed(obj)    // → false
Object.seal(obj)
Object.isSealed(obj)    // → true

Use Object.isSealed() to check whether an object's properties cannot be added or removed (though values may still change).

Object.isSealed() — frozen implies sealed

Since Object.freeze() makes an object non-extensible and all properties non-configurable (and non-writable), a frozen object is always also sealed.

Challenge: Demonstrate that a frozen object is also sealed.

💡 Hints (1)