JavaScript Reflect.isExtensible() Method

The static Reflect.isExtensible() method is used to check if an object is extended or not. This method is similar to Object.isExtensible() but with some difference.

Syntax:

Parameters:

Obj: It is the target object which to check if it is extensible.

Return value:

This method returns a Boolean which indicates whether or not the target is extensible.

Exceptions:

A TypeError, if the target is not an Object.

Browser Support:

Chrome	49
Edge	12
Firefox	42
Opera	36

Example 1

const object = {};
console.log(Reflect.isExtensible(object));
Reflect.preventExtensions(object);
console.log(Reflect.isExtensible(object));

Output:

true
 false

Example 2

const object2 = Object.seal({});

console.log(Reflect.isExtensible(object2));

const object3 = Object.seal({});
console.log(Reflect.isExtensible(object3));

Output:

 false
 false

Example 3

const object = {};
const object1 = {};
console.log(Reflect.isExtensible(object1));
Reflect.preventExtensions(object);
console.log(Reflect.isExtensible(object));

Output: