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.src=fr.result;
        img.onload = function() {
            alert(img.width);
        };
    };
    fr.readAsDataURL(this.files[0]);
});