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Object-Oriented Programming in JavaScript
course content

Course Content

Object-Oriented Programming in JavaScript

Object-Oriented Programming in JavaScript

1. Classes & Objects
ClassesClass AttributesClass MethodsObjects' Creating Keyword 'this'Constructor
2. Encapsulation
Private ModifierGet and Set
3. Static
Static AttributesStatic Functions
4. Inheritance
What is an InheritanceConstructor InheritanceOverriding

bookStatic Functions

Methods also can be static. Let’s create compare() method with two parameters: studentA and studentB. This function will output which student has a higher GPA.


              
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class Student{
  name;
  age;
  static ageOfMajority = 18;
  university;
  gpa;
  constructor(name, age){
    this.name = name;
    this.age = age;
    console.log('Student created');
  }

  static compare(studentA, studentB) {
    if (studentA.gpa > studentB.gpa) { console.log('First student has higher GPA.') }
    else if (studentA.gpa < studentB.gpa) { console.log('Second student has higher GPA.') }
    else { console.log('GPAs are equal.') }
}
}

rob = new Student('Robert', 22);
rob.gpa = 3.4;
steve = new Student('Steve', 19);
steve.gpa = 2.9
Student.compare(rob, steve);
copy

To call this method, you also have to use the name of the class, not the object:


              
1

            
Student.compare(studentA, studentB);
copy

Inside the static method, you can refer only to static class attributes, using this keyword, because non-static attributes are unique for each object, so for the whole class, they are undefined.

Note that in function compare() you refer to the non-static objects attributes studentA and studentB, but to the static class attributes Student.

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Section 3. Chapter 2
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bookStatic Functions

Methods also can be static. Let’s create compare() method with two parameters: studentA and studentB. This function will output which student has a higher GPA.


              
123456789101112131415161718192021222324

            
class Student{
  name;
  age;
  static ageOfMajority = 18;
  university;
  gpa;
  constructor(name, age){
    this.name = name;
    this.age = age;
    console.log('Student created');
  }

  static compare(studentA, studentB) {
    if (studentA.gpa > studentB.gpa) { console.log('First student has higher GPA.') }
    else if (studentA.gpa < studentB.gpa) { console.log('Second student has higher GPA.') }
    else { console.log('GPAs are equal.') }
}
}

rob = new Student('Robert', 22);
rob.gpa = 3.4;
steve = new Student('Steve', 19);
steve.gpa = 2.9
Student.compare(rob, steve);
copy

To call this method, you also have to use the name of the class, not the object:


              
1

            
Student.compare(studentA, studentB);
copy

Inside the static method, you can refer only to static class attributes, using this keyword, because non-static attributes are unique for each object, so for the whole class, they are undefined.

Note that in function compare() you refer to the non-static objects attributes studentA and studentB, but to the static class attributes Student.

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

Section 3. Chapter 2
toggle bottom row

bookStatic Functions

Methods also can be static. Let’s create compare() method with two parameters: studentA and studentB. This function will output which student has a higher GPA.


              
123456789101112131415161718192021222324

            
class Student{
  name;
  age;
  static ageOfMajority = 18;
  university;
  gpa;
  constructor(name, age){
    this.name = name;
    this.age = age;
    console.log('Student created');
  }

  static compare(studentA, studentB) {
    if (studentA.gpa > studentB.gpa) { console.log('First student has higher GPA.') }
    else if (studentA.gpa < studentB.gpa) { console.log('Second student has higher GPA.') }
    else { console.log('GPAs are equal.') }
}
}

rob = new Student('Robert', 22);
rob.gpa = 3.4;
steve = new Student('Steve', 19);
steve.gpa = 2.9
Student.compare(rob, steve);
copy

To call this method, you also have to use the name of the class, not the object:


              
1

            
Student.compare(studentA, studentB);
copy

Inside the static method, you can refer only to static class attributes, using this keyword, because non-static attributes are unique for each object, so for the whole class, they are undefined.

Note that in function compare() you refer to the non-static objects attributes studentA and studentB, but to the static class attributes Student.

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

Methods also can be static. Let’s create compare() method with two parameters: studentA and studentB. This function will output which student has a higher GPA.


              
123456789101112131415161718192021222324

            
class Student{
  name;
  age;
  static ageOfMajority = 18;
  university;
  gpa;
  constructor(name, age){
    this.name = name;
    this.age = age;
    console.log('Student created');
  }

  static compare(studentA, studentB) {
    if (studentA.gpa > studentB.gpa) { console.log('First student has higher GPA.') }
    else if (studentA.gpa < studentB.gpa) { console.log('Second student has higher GPA.') }
    else { console.log('GPAs are equal.') }
}
}

rob = new Student('Robert', 22);
rob.gpa = 3.4;
steve = new Student('Steve', 19);
steve.gpa = 2.9
Student.compare(rob, steve);
copy

To call this method, you also have to use the name of the class, not the object:


              
1

            
Student.compare(studentA, studentB);
copy

Inside the static method, you can refer only to static class attributes, using this keyword, because non-static attributes are unique for each object, so for the whole class, they are undefined.

Note that in function compare() you refer to the non-static objects attributes studentA and studentB, but to the static class attributes Student.

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Section 3. Chapter 2
Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
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