question mark when accessing property javascript

Optional chaining: (?.)

The optional chaining operator (?.) enables you to 
read the value of a property located deep within a 
chain of connected objects without having to 
check that each reference in the chain is valid.

The ?. operator is like the . chaining operator, 
except that instead of causing an error if a reference 
is nullish (null or undefined), the expression returns 
a value of undefined. 

When used with function calls, 
it returns undefined if the given function does not exist.

Example:

const adventurer = {
  name: 'Alice',
  cat: {
    name: 'Dinah'
  }
};

const dogName = adventurer.dog?.name;
console.log(dogName);
// output: undefined

console.log(adventurer.someNonExistentMethod?.());
// output: undefined