title: Deselecting above checkboxes (a "none of above" option)
body: <p>I am working on this demo. How I can fix the code for last checkbox in a way to deselect all of above checkboxes when check and do nothing on un-check states?</p>
  
  <pre><code>&lt;input id="selectAll" type="checkbox" name="slectAll"&gt;
  &lt;label for="selectAll"&gt;Yes, Select All&lt;/label&gt;
  &lt;fieldset id="group_1"&gt;
     &lt;input type="checkbox" name="numbers[]" value="0" /&gt;Item 1&lt;br /&gt;
    &lt;input type="checkbox" name="numbers[]" value="1" /&gt;Item 2&lt;br /&gt;
    &lt;input type="checkbox" name="numbers[]" value="2" /&gt;Item 3&lt;br /&gt;
    &lt;input type="checkbox" name="numbers[]" value="3" /&gt;Item 4&lt;br /&gt;
    &lt;input type="checkbox" name="numbers[]" value="4" /&gt;Item 5&lt;br /&gt;
  &lt;/fieldset&gt;
  &lt;input id="planB" type="checkbox" name="planB"&gt;
  &lt;label for="planB"&gt;I am not Sure&lt;/label&gt;
  
  &lt;script&gt;
  $(function() {
    var $all = $('input:checkbox[name=slectAll]').change(function() {
      $checks.prop("checked", this.checked);
    });
  
    var $checks = $('#group_1 :checkbox').change(function() {
      $all.prop("checked", $checks.not(':checked').length == 0);
    });
  
    var $none = $('input:checkbox[name=planB]').change(function() {
      $checks.prop("checked", this.checked);
    });    
  
   });    
  &lt;/script&gt;
  </code></pre>