JSFiddle - React, Tailwind, and code Playground

JavaScript

var Animal = new Class({
    initialize: function(age){
        this.age = age;
    }
});

var Cat = new Class({
    Extends: Animal,
    initialize: function(name, age){
        // calls initalize method of Animal class
        this.parent(age);
        this.name = name;
    }
});

var myCat = new Cat('Micia', 20);
alert(myCat.name); // alerts 'Micia'.
alert(myCat.age); // alerts 20.