HTML

how to change hidden on html

$('#check').change(function() {
  $("#delete").prop("hidden", !this.checked);
})

how to change hidden on html

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<table>
  <tr>
    <td>
      <input id="check" type="checkbox" name="del_attachment_id[]" value="<?php echo $attachment['link'];?>">
    </td>

    <td id="delete" hidden="true">
      the file will be deleted from the newsletter
    </td>
  </tr>
</table>