Exam JS-Dev-101 Topic 1 Question 17 Discussion

The verified answer is A.
This constructor function runs when new Person() is called:
function Person() {
this.firstName = "John";
}
So this line:
const myFather = new Person();
creates an object like this:
{
firstName: "John"
}
Then the prototype is assigned a method named job:
Person.prototype = {
job: x => "Developer"
};
Because myFather is created from Person, it can access properties and methods from Person.prototype.
So:
myFather.firstName
returns:
"John"
And:
myFather.job()
returns:
"Developer"
Therefore:
const result = myFather.firstName + " " + myFather.job();
becomes:
const result = "John" + " " + "Developer";
Final value:
"John Developer"
Option B is incorrect because job() returns "Developer", not undefined.
Option C is incorrect because job exists on Person.prototype, so it is callable.
Option D is incorrect because firstName is assigned inside the constructor.
Therefore, the verified answer is A.