Optional Chaining ?.

Chaining operator will give us undefined when reference that we want to use is nullish instead of error, it's very usefull when the content of an object don't have guarantee as to which properties are required

const ourObject = {
    name:'Alina',
    pet:{
        name:'kitty',
        type:'cat'
    }
}
const dogName = ourObject.dog.name;
console.log(dogName)

Because dog is not exist at ourObject then it will return Uncaught TypeError: Cannot read property 'name' of undefined

To prevent those error we can use optional chaining, so instead of error this code will return undefined

const dogName = ourObject.dog?.name
console.log(dogName)
// Undefined

It also work for checking methods inside object

console.log(ourObject.nonEksistingMethod())
//Uncaught TypeError: ourObject.someNonExistentMethod is not a function

console.log(ourObject.someNonExistentMethod?.())
// Undefined