JSFiddle - React, Tailwind, and code Playground

by Alexis LĂłpez Espinoza

HTML

<input type = "file" />

JavaScript

var file = document.getElementsByTagName("input")[0];

file.addEventListener("change", function(){
    var fileSize = this.files[0].size,
        mb = 1048576,
        final = fileSize / mb;
    alert(final.toFixed(2) + " MB");
}, false);