Find element by class under the same parent

Any particular reason about this isn't matching the element with that class? I have checked a million times and can't see what is that I'm doing wrong.

$('.lnk-folder').click(function(e) {
  e.preventDefault();
  var header = $(this).parent('thead').find('.folder-header');
  console.log($(header));
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<thead>
  <tr>
    <th colspan="10" style="padding:0px; font-size:120%;background-color:#ff0000;">
      <div style="float:left;min-width:20%;">
        <a style="color: #000" class="lnk-folder folder-close" data-hash="" href="#">
          <i class='fa fa-folder-open'></i> Folder 1
        </a>
      </div>
      <div style="float:left;height:26px;padding-left:10px;">
        <a href="#"><i class='fas fa-file-upload tooltip' style="color:#fff;"><span class="tooltiptext_m">New</span></i></a>
      </div>
    </th>
  </tr>
  <tr class="folder-header">
    <th colspan="2" style='background-color:#0c343d;vertical-align:middle;'> Name </th>
    <th style='width:7%;background-color:#0c343d;vertical-align:middle;'> Code </th>
    <th style='width:30%;background-color:#0c343d;vertical-align:middle;'> Act</th>
    <th style='width:7%;background-color:#0c343d;vertical-align:middle;'> Version</th>
  </tr>
</thead>

Solution

parent() is your problem. It looks up the DOM exactly one level, to the parent element, but you need to go higher than that. To do so, use closest()

$('.lnk-folder').click(function(e) {
  e.preventDefault();
  var header = $(this).closest('thead').find('.folder-header');
  console.log($(header));
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<table>
  <thead>
    <tr>
      <th colspan="10" style="padding:0px; font-size:120%;background-color:#ff0000;">
        <div style="float:left;min-width:20%;">
          <a style="color: #000" class="lnk-folder folder-close" data-hash="" href="#">
            <i class='fa fa-folder-open'></i> Folder 1
          </a>
        </div>
        <div style="float:left;height:26px;padding-left:10px;">
          <a href="#"><i class='fas fa-file-upload tooltip' style="color:#fff;"><span class="tooltiptext_m">New</span></i></a>
        </div>
      </th>
    </tr>
    <tr class="folder-header">
      <th colspan="2" style='background-color:#0c343d;vertical-align:middle;'> Name </th>
      <th style='width:7%;background-color:#0c343d;vertical-align:middle;'> Code </th>
      <th style='width:30%;background-color:#0c343d;vertical-align:middle;'> Act</th>
      <th style='width:7%;background-color:#0c343d;vertical-align:middle;'> Version</th>
    </tr>
  </thead>
</table>