JSFiddle - React, Tailwind, and code Playground

HTML

<div>Vector</div>
<div><span>X: </span><span id="x"></span><div>
<div><span>Y: </span><span id="y"></span></div>

JavaScript

var Vector = function(x,y){
 this.x = x;
 this.y = y;
}
var Collidable = function Collidable(x, y, d){
    this.pos = new Vector(x, y) || new Vector(50, 50);
}
var Player = function Player(){
    this.health = 100;
}
Player.prototype = new Collidable(50, 50, 70);

var current = new Player();

console.log(current);
console.log(current.pos);

document.getElementById("x").innerHTML = current.pos.x;
document.getElementById("y").innerHTML = current.pos.y;