JSFiddle - React, Tailwind, and code Playground

HTML

<table class='list_table'>
<input type='file' class='form_textbox' name='"LicenseCk1' size='40'>
<input type='file' class='form_textbox' name='"LicenseCk2' size='40'>
<input type='file' class='form_textbox' name='"LicenseCk3' size='40'>
</table>
<script
  src="https://code.jquery.com/jquery-1.12.4.js"
  integrity="sha256-Qw82+bXyGq6MydymqBxNPYTaUXXq7c8v3CwiYwLLNXU="
  crossorigin="anonymous"></script>

JavaScript

$('body').on('change','.form_textbox',function(){
    alert($(this).attr('size'));
});