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JavaScript Object-Oriented JavaScript (2015) Prototypal Inheritance Setting Up the Prototype Chain

vishal gupta
vishal gupta
4,920 Points
Posted by vishal gupta
vishal gupta
4,920 Points

You're going to modify the Teacher code to inherit from the Person. First, in the Teacher constructor function, call the

I am getting this error-------You don't need to set the firstName or lastName properties, the Person.call will handle that!................Please help!

person.js 
function Person(firstName, lastName) {
  this.firstName = firstName;
  this.lastName = lastName;
}

Person.prototype.fullName = function() {
 return this.firstName + " " + this.lastName; 
};
teacher.js 
function Teacher(firstName, lastName, roomNumber) {
  Person.call(this,firstName,lastName);
  this.firstName = firstName;
  this.lastName = lastName;
  this.room = roomNumber;
}
Teacher.prototype = Object.create(Person.prototype);
Ashu Singh
Ashu Singh
253 Points

You should remove the default code for firstName and lastName in teacher.js because you're calling the same thing from person.js.

function Teacher(firstName, lastName, roomNumber) {
  Person.call(this,firstName,lastName);
  this.room = roomNumber;
}

1 Answer

Jesus Mendoza
Jesus Mendoza
23,288 Points
Jesus Mendoza
Jesus Mendoza
23,288 Points

You don't need to define 

this.firstName = firstName;
this.lastName = lastName;

inside the Teacher's object because you are already inheriting those properties from the person object using 

Person.call(this, firstName, lastName)

Now, when you create an instance of Teacher, the Person.call function will be executed and you will have firstName and lastName inside your new Teacher instance because you inherited from the Person's object.