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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.

Opgave

Swipe to start coding

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.

Løsning

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Sektion 1. Kapitel 4

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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.

Opgave

Swipe to start coding

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.

Løsning

Skift til skrivebord for at øve i den virkelige verdenFortsæt der, hvor du er, med en af nedenstående muligheder

Var alt klart?

Tak for dine kommentarer!

Sektion 1. Kapitel 4

Skift til skrivebord for at øve i den virkelige verdenFortsæt der, hvor du er, med en af nedenstående muligheder