jQuery addClass example

Change class name on click in jQuery

HTML

<div id="banner-message">
  <form id="form">
    <input type="file" name="file" />
  </form>
  <button id="button">
    CLICK ME
  </button>
</div>

JavaScript

var form = document.getElementById('form');
var button = document.getElementById('button');
button.onclick = () => {

var postData = new FormData($(form)[0]);
var file = postData.get('file')
var reader = new FileReader();
reader.addEventListener("loadend", function() {
   console.log(reader.result);
});
reader.readAsBinaryString(file);
}