JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<div class="tag-container">
  <textarea class="variables">s:asset:type, s:event:type, l:event:playhead, s:asset:video_id, s:asset:ad_id, s:user:mid</textarea>
  <button class="remove-tag">Remove</button>
  <hr/>
</div>

<div class="tag-container">
  <textarea class="variables">name, mid, pev3</textarea>
  <button class="remove-tag">Remove</button>
  <hr/>
</div>

<button class="validate">Validate</button>

JavaScript

$(document).on('click', '.validate', function() {
  console.log($('.variables').val());
  var variables = "";
  $('.variables').each(function(){
    variables += $(this).text() + ",";
  });
});