The Object isExtensible() method

Find out all about the JavaScript isExtensible() method of the Object object

This method checks if we can add new properties to an object.

Any object is extensible, unless it’s been used as an argument to

• Object.freeze()
• Object.seal()
• Object.preventExtensions()

Usage:

const dog = {}
Object.isExtensible(dog) //true

const cat = {}
Object.freeze(cat)
Object.isExtensible(cat) //false