JSFiddle - React, Tailwind, and code Playground

HTML

<span class="window-size"></span>

JavaScript

function sizeOfThings(){
  var windowWidth = window.innerWidth;
  var windowHeight = window.innerHeight;
  
  var screenWidth = screen.width;
  var screenHeight = screen.height;
  
  document.querySelector('.window-size').innerHTML = windowWidth;

};
sizeOfThings();

window.addEventListener('resize', function(){
	sizeOfThings();
});