JSFiddle - React, Tailwind, and code Playground

JavaScript

(function() {
    var ids = {};
    
    function Vehicle() {
        
    }

    Vehicle.prototype.applyVars = function() {
        var name = this.constructor.name,
            id   = ids[name];
        
        if(!id) {
            id = ids[name] = 0;
        }
        
        this.id = name + "-" + id;
        
        ids[name]++;
    };
    
    function Car() {
        this.applyVars();
    }
    
    function Truck() {
        this.applyVars();
    }
    
    Car.prototype = new Vehicle;
    Car.prototype.constructor = Car;
    
    Truck.prototype = new Vehicle;
    Truck.prototype.constructor = Truck;
    
    window.Vehicle = Vehicle;
    window.Car = Car;
    window.Truck = Truck;
})();

var car1   = new Car,
    car2   = new Car,
    truck1 = new Truck;

alert([car1.id, car2.id, truck1.id]);