JSFiddle - React, Tailwind, and code Playground

by pimvdb

HTML

<input type="file">

JavaScript

$('input').change(function() {
    
    var fr = new FileReader;
    
    fr.onload = function() {
        var img = new Image;
        
        img.onload = function() {
            alert(img.width);
        };
        
        img.src = fr.result;
    };
    
    fr.readAsDataURL(this.files[0]);
    
});