Course Content

Object-Oriented Programming in JavaScript

1. Classes & Objects

Classes Class Attributes Class Methods Objects' Creating Keyword 'this'Constructor

2. Encapsulation

Private Modifier Get and Set

3. Static

Static Attributes Static Functions

4. Inheritance

What is an Inheritance Constructor Inheritance Overriding

Objects' Creating

The object is an instance of some class. For example, for our class Rectangle, which describes some figures, we can create two figures:


              12
            
figure1 = new Rectangle();
figure2 = new Rectangle();

There are two different objects, which are instances of Rectangle() class.

Now we’ll create two students:


              12
            
student1 = new Student();
student2 = new Student();

These two objects have predefined methods and attributes. name, university, gpa, and age have undefined values.

To init or change the attribute’s value for an object, you can simply refer to it. Same you can do if you want to get the value of this attribute:


              123
            
student1.name = 'Julia';
student1.age = 18;
console.log('Age of the first student is:', student1.age);

There is a simple way to detect which values object's attributes have: call console.log(object_name) and you'll see the JSON string that looks like:


              123456
            
Student { // name of the class
  name: undefined, // attribute and its value
  university: undefined,
  age: undefined,
  gpa: undefined
}

There is a similar syntax to call the method:


              1
            
student2.sleep();

Note that you can't create an instance of the class before the defintion of this class.

You can set some default name for attribute inside a class:


              123456789101112
            
class Student{
  name;
  university = 'MIT';
  age = 18;
  gpa;
  sleep(){
    console.log('I am sleeping right now!');
  }
  happyBirthday(){
    console.log('Today is my birthday!');
  }
}

Now all objects will have undefined value of gpa and name, but predefined values of age and university.

You refer to methods and some single object attributes, so you’ll work with data in it.

Each object has a unique value of attributes, i. e. if you change the name for student1, the name of student2 doesn’t change.

Class notation is a formal and common representation of the behavior of different objects of this class.

Task

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Set some default values for all Student class attributes. Then create object of class Student and output values of all the attributes for this object. In the end, call the sleep() method.

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Thanks for your feedback!

Section 1. Chapter 4

Objects' Creating

The object is an instance of some class. For example, for our class Rectangle, which describes some figures, we can create two figures:


              12
            
figure1 = new Rectangle();
figure2 = new Rectangle();

There are two different objects, which are instances of Rectangle() class.

Now we’ll create two students:


              12
            
student1 = new Student();
student2 = new Student();

These two objects have predefined methods and attributes. name, university, gpa, and age have undefined values.

To init or change the attribute’s value for an object, you can simply refer to it. Same you can do if you want to get the value of this attribute:


              123
            
student1.name = 'Julia';
student1.age = 18;
console.log('Age of the first student is:', student1.age);

There is a simple way to detect which values object's attributes have: call console.log(object_name) and you'll see the JSON string that looks like:


              123456
            
Student { // name of the class
  name: undefined, // attribute and its value
  university: undefined,
  age: undefined,
  gpa: undefined
}

There is a similar syntax to call the method:


              1
            
student2.sleep();

Note that you can't create an instance of the class before the defintion of this class.

You can set some default name for attribute inside a class:


              123456789101112
            
class Student{
  name;
  university = 'MIT';
  age = 18;
  gpa;
  sleep(){
    console.log('I am sleeping right now!');
  }
  happyBirthday(){
    console.log('Today is my birthday!');
  }
}

Now all objects will have undefined value of gpa and name, but predefined values of age and university.

You refer to methods and some single object attributes, so you’ll work with data in it.

Each object has a unique value of attributes, i. e. if you change the name for student1, the name of student2 doesn’t change.

Class notation is a formal and common representation of the behavior of different objects of this class.

Task

Swipe to show code editor

Set some default values for all Student class attributes. Then create object of class Student and output values of all the attributes for this object. In the end, call the sleep() method.

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Thanks for your feedback!

Section 1. Chapter 4

Switch to desktop for real-world practiceContinue from where you are using one of the options below