Question

How do you prevent an object to extend in Javascript?

Answer 1

The Object.preventExtensions() method is used to prevent new properties from ever being added to an object. In other words, it prevents future extensions to the object. Let's see the usage of this property,

const newObject = {};
Object.preventExtensions(newObject); // NOT extendable

try {
  Object.defineProperty(newObject, "newProperty", {
    // Adding new property
    value: 100,
  });
} catch (e) {
  console.log(e); // TypeError: Cannot define property newProperty, object is not extensible
}