JSFiddle - React, Tailwind, and code Playground

JavaScript

var Car = new Class({
    initialize: function (make) {
        this.make = make;
        this.currentSpeed = 25;
    },

    printCurrentSpeed: function () {
        console.log(this.make + ' is going ' + this.currentSpeed + ' mph.');
    }
})

var RaceCar = new Class({ //inheritance
    Extends: Car,
    initialize: function (make, topSpeed) {
        this.parent(topSpeed)
        this.topSpeed = topSpeed;
    },

    goFast: function () {
        this.currentSpeed = this.topSpeed;
    }
})

var stang = new RaceCar('Mustang', 150);

stang.printCurrentSpeed();
stang.goFast();
stang.printCurrentSpeed();