What are JavaScript classes?

Classes are in fact special functions, and just as you can define function expressions and function declarations, the class syntax has two components: class expressions and class declarations.

Reference Material:

• MDN

• JS.info

Example:

class Rectangle {
  constructor(height, width) {
    this.height = height;
    this.width = width;
  }
}

How does Inheritance work with classes?

Classes inherit via the extends keyword. extends tells the new class that you create that it is the child of the following class name. Once a class is extended you also need to use the super() function to tell the parent class that it now has a child.

Example:

// Parent class
class Animals {
  constructor(attributes) {
      this.animalCommonName = attributes.animalCommonName;
      this.weight = attributes.weight;
      this.height = attributes.height;
      this.food = attributes.food;
  }
  
  eat() {
    return `The ${this.animalCommonName} eats ${this.food}`;
  }
}

// Child class
// Extends: "Hey, Dog, Animals is your parent! Grab everything from them."
// super(): "Hey, Animals, Dog is your child, give them everything they need."
class Dog extends Animals {
  constructor(dogAttribs) {
    super(dogAttribs);
    this.name = dogAttribs.name;
    this.bark = dogAttribs.bark;
  }
  speak() {
    return `${this.name} says: ${this.bark}`;
  }
}