JSFiddle - React, Tailwind, and code Playground

HTML

<h1>
Look at console
</h1>
<br>
<input
  id = 'input'
  type = 'file'
  value = 'click'
/>

JavaScript

/**
* get an image's dimensions using pure js
*/


var input = document.getElementById('input');

input.addEventListener("change", function() {
	var file  = this.files[0];
  var img = new Image();
  
	img.onload = function() {
    var sizes = {
    	width:this.width,
      height: this.height
    };
    URL.revokeObjectURL(this.src);
    
    console.log('onload sizes', sizes);
    console.log('onload this', this);
	}

  var objectURL = URL.createObjectURL(file);
  
  console.log('change: file', file);
  console.log('change: objectURL', objectURL);
  img.src = objectURL;
});