Static method Object.isExtensible()

The Object.isExtensible() static method determines
if an object is extensible (whether it can have
new properties added to it).

const object1 = {};

console.log(Object.isExtensible(object1));
// Expected output: true

Object.preventExtensions(object1);

console.log(Object.isExtensible(object1));
// Expected output: false