JSFiddle - React, Tailwind, and code Playground

HTML

<p id="two"></p>

JavaScript

function Rectangle(w, h){
	this.width = w;
	this.height = h;
}

this.getArea = function(){
	return this.width * this.height;
}
var rect = new Rectangle(100, 50);
	document.getElementById('two').innerHTML = ('Площадь прямоугольника ' + rect.getArea());