JSFiddle - React, Tailwind, and code Playground

HTML

<img src="http://www.webdesignbooth.com/wp-content/uploads/2009/08/dyrholaey-landscape.jpg" id="myimg" style="max-width: 100px" />

JavaScript

var i = document.getElementById('myimg');

var i2 = new Image();
i2.onload = function() {
   alert(i2.width);
};

i2.src = i.src;