Static Methods

Static methods are methods that are available on the class itself. They are not available on the instances of the class. Static methods are often used to create utility functions or to hold data that is shared across all instances of the class. Let's create our Shape and Rectangle class from the previous example and add a static method called getClassName.

A static method is created the same way as a regular method. The only difference is that we use the static keyword.

class Shape {
  constructor(name) {
    this.name = name;
  }

  logName() {
    console.log(this.name);
  }

  static getClassName() {
    return 'Shape';
  }
}

class Rectangle extends Shape {
  constructor(name, height, width) {
    super(name);
    this.height = height;
    this.width = width;
  }

  area() {
    return this.height * this.width;
  }

  static getClassName() {
    return 'Rectangle';
  }
}

Let's try to crate an instance of a Rectangle and call the getClassName method.

const rect = new Rectangle('Rectangle', 10, 20);

rect.getClassName(); // TypeError: rect.getClassName is not a function

This does not work, because the getClassName method is not available on the instance of the Rectangle class. It is only available on the class itself.

console.log(Shape.getClassName());
console.log(Rectangle.getClassName());

So if you have a method where you don't need to access the instance of the class, you can make it a static method. This way you can call it directly on the class.