Static Attributes

As you already know, each object can have a unique attribute value, like, for example, studentA has name Andrew and studentB has name William. But sometimes it makes sense to set some static value - the common for all instances of the class.

Let's add a attribute called ageOfMajority. Obviously, the value is 18 for all Students’ objects, and can't be different for different students. We’ll add a static keyword.


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

student = new Student('Robert', 22);

console.log(Student.ageOfMajority);

To refer to the static attribute, use the name of the class, not the object, because it is a property of the class.

Inside non-static functions, you can refer static attribute only using class name, not this keyword. Look how we refer non-static age and static ageOfMajority in method drink():


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class Student{
  name;
  age;
  static ageOfMajority = 18;
  constructor(name, age){
    this.name = name;
    this.age = age;
    console.log('Student created');
  }
  drink(){
    if (this.age < Student.ageOfMajority){
      console.log('I am too young, only', this.age, 'yrs old.');
    } else {
      console.log('I am drunk.');
    }
  }
}

student = new Student('Robert', 22);

student.drink();

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Let's create function interview(), which assigns a student to the class A, if GPA >= 3.0, or class B if not. For this, define static attribute gpaLimit and assign it with 3.0, and inside interview() function compare it with student's GPA. Print message Assigned to the class A or Assigned to the class B.

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Sección 3. Capítulo 1

Static Attributes

Let's add a attribute called ageOfMajority. Obviously, the value is 18 for all Students’ objects, and can't be different for different students. We’ll add a static keyword.


              1234567891011121314
            
class Student{
  name;
  age;
  static ageOfMajority = 18
  constructor(name, age){
    this.name = name;
    this.age = age;
    console.log('Student created');
  }
}

student = new Student('Robert', 22);

console.log(Student.ageOfMajority);

To refer to the static attribute, use the name of the class, not the object, because it is a property of the class.

Inside non-static functions, you can refer static attribute only using class name, not this keyword. Look how we refer non-static age and static ageOfMajority in method drink():


              123456789101112131415161718192021
            
class Student{
  name;
  age;
  static ageOfMajority = 18;
  constructor(name, age){
    this.name = name;
    this.age = age;
    console.log('Student created');
  }
  drink(){
    if (this.age < Student.ageOfMajority){
      console.log('I am too young, only', this.age, 'yrs old.');
    } else {
      console.log('I am drunk.');
    }
  }
}

student = new Student('Robert', 22);

student.drink();

Tarea

Swipe to show code editor

Cambia al escritorio para practicar en el mundo realContinúe desde donde se encuentra utilizando una de las siguientes opciones

¿Todo estuvo claro?

¡Gracias por tus comentarios!

Sección 3. Capítulo 1

Cambia al escritorio para practicar en el mundo realContinúe desde donde se encuentra utilizando una de las siguientes opciones