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

Posted by Bozin Madenski
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Bozin Madenski
Full Stack JavaScript Techdegree Student 773 Points

what the ..?

Bummer! The Person.call method needs this, firstName and lastName, in that order!

I'm so confused right now.

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

1 Answer

Valeriya Romashchenko
Valeriya Romashchenko
11,841 Points
Valeriya Romashchenko
Valeriya Romashchenko
11,841 Points

When you call constructor Person inside of the Teacher constructor it is called inheritance. Teacher Inherits the properties for firstName and lastName from constructor Person, that is why inside of the Teacher you need to delete these properties because otherwise, you repeat yourself and duplicate the same properties twice. In other words, your code in theacher.js should be like this:

function Teacher(firstName, lastName, roomNumber) {
  this.room = roomNumber;
  Person.call(this, firstName, lastName)
}
Valeriya Romashchenko
Valeriya Romashchenko
11,841 Points

It passed the challenge