JSFiddle - React, Tailwind, and code Playground

HTML

<div id="i1"></div>
<div id="e1" title="expected">3|226|130|172</div>

JavaScript

$d = $('#i1');
$d.text('hey');

var b = new Blob(['€']);
var fr = new FileReader();
fr.onload = function() {
    ua = new Uint8Array(fr.result);
    $d.text(fr.result.byteLength + '|' + ua[0]  + '|' + ua[1] + '|' + ua[2] + '');
};
fr.readAsArrayBuffer(b);