JavaScript Classes and Inheritance (ES6)
According to ES6, you can use JavaScript classes and inheritance to accomplish what you need.
JavaScript classes, introduced in ECMAScript 2015, are primarily syntactical sugar over JavaScript’s existing prototype-based inheritance.
Reference: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes
First of all, we define our abstract class. This class can’t be instantiated, but can be extended.
We can also define functions that must be implemented in all classes that extends this one.
/**
* Abstract Class Animal.
*
* @class Animal
*/
class Animal {
constructor() {
if (this.constructor == Animal) {
throw new Error("Abstract classes can't be instantiated.");
}
}
say() {
throw new Error("Method 'say()' must be implemented.");
}
eat() {
console.log("eating");
}
}
After that, we can create our concrete Classes. These classes will inherit all functions and behaviour from abstract class.
/**
* Dog.
*
* @class Dog
* @extends {Animal}
*/
class Dog extends Animal {
say() {
console.log("bark");
}
}
/**
* Cat.
*
* @class Cat
* @extends {Animal}
*/
class Cat extends Animal {
say() {
console.log("meow");
}
}
/**
* Horse.
*
* @class Horse
* @extends {Animal}
*/
class Horse extends Animal {}
And the results…
// RESULTS
new Dog().eat(); // eating
new Cat().eat(); // eating
new Horse().eat(); // eating
new Dog().say(); // bark
new Cat().say(); // meow
new Horse().say(); // Error: Method say() must be implemented.
new Animal(); // Error: Abstract classes can't be instantiated.