Classes

Classes are a template for creating objects and are built on prototypes.

class MyClass {
  constructor() {}
  method1() {}
}

Instances are created by using the new keyword.

const aClass = new MyClass();

Classes automatically use the prototype to store functions.

Class expressions

Classes, like functions, can be passed around to function calls and in variables. This is done by assigning the class to a variable.

let User = class {
  sayHi() {
    alert("Hello");
  }
};

Getters and Setters

Classes can have getters and setters defined.

class Person {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }

  get nameAndAge() {
    return `${this.name} is ${this.age} years old`;
  }
}

const bob = new Person("bob", 25);

console.log(bob.nameAndAge); // outputs "bob is 25 years old"

Inheritance

Inheritance can be implemented in JavaScript through the use of the extends keyword.

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

  speak() {
    console.log(`${this.name} makes a noise.`);
  }
}

class Dog extends Animal {
  constructor(name) {
    super(name); // call the super class constructor and pass in the name parameter
  }

  speak() {
    console.log(`${this.name} barks.`);
  }
}

const d = new Dog("Mitzie");
d.speak(); // Mitzie barks.