Is there a built-in "None of the above" checkbox option in webform? and how to create one? I may be mistaken but I recall seeing such option in webform somewhere before and I don't seem to find it now (in case I'm right). (please see last edit)
I have several questions with big lists of checkboxes and if there's such option buil-in webform it would be great and better than having to do it via a custom jQuery code.
Thank you
EDIT:
This is a sample question with a
  mywfq:
    '#type': checkboxes
    '#title': 'Please chcek all that applies'
    '#options':
      q1: '....'
      q2: '....'
      q3: '....'
      q4: '.....'
      q5: '.....'
    '#attributes':
      class:
        - mywfq
    '#format_items': ol
  mwwfqnota:
    '#type': checkbox
    '#title': 'None of the above'
    '#attributes':
      class:
        - nota

In the above, I created a separate single checkbox element after the multi one and tried to use jQuery to uncheck all the above if this is checked but it's not working yet.
This is my code:
 $(&quot;input.mywfq).change(function() {
 $(&quot;input.nota&quot;).not(this).prop('checked', false);
  });

$(&quot;input.nota).on('change', function() {
$(&quot;input.mywfq&quot;).not(this).prop('checked', false);
 });

I'm still wondering if no already such built-in option!
EDIT: the great Webform team seems to have added the &quot;none of the above&quot; option to the module (x6 but not sure about prev versions).
This code was fine but wasn't working due to iCheck enabled and then checkboxes "aren't" cleared when the "None of the above" is checked although the counting of checked ones was updating correctly (actually the checked state IS cleared but their iCheck-added class is not and that's why their apparent checked state keeps looking as checked). I'll try find a fix to keep iCheck and make it work with maybe later but for now the following works as expected.

So for anyone that may need this.
Create a single checkbox element after the one with multi checkboxes and call it "None of the above" and give it an element custom css ( I called it 'nota' ) to use in the jQuery code to toggle checked status between the 'nota' and all other checkboxes. 

 $("input.mywfq).change(function() {
 $("input.nota").not(this).prop('checked', false);
  });

$("input.nota).on('change', function() {
$("input.mywfq").not(this).prop('checked', false);
 });


IMPORTANT: make sure iCheck is set to "none" for this element in case its enabled for the form by default.