JS Practice — Built-in Objects

Object.isExtensible() — after preventExtensions

📖 Usage Example

// Check if new properties can be added
const obj = { a: 1 }
Object.isExtensible(obj)             // → true
Object.preventExtensions(obj)
Object.isExtensible(obj)             // → false

Use Object.isExtensible() to check whether new properties can still be added to an object.

Object.isExtensible() after preventExtensions

Once Object.preventExtensions(obj) is called, the object cannot have new properties added.

Challenge: Write a function that calls Object.preventExtensions and returns whether the result is extensible.

💡 Hints (1)

• All of freeze, seal, and preventExtensions make an object non-extensible