title: knockout check/uncheck all combo box
body: <p>I using knockout for mapping JSON obejct to user control, I have a list of single checkboxes,
  They look like </p>
  
  <pre><code> &lt;input type="checkbox" data-bind="checked: IsEnabled1" /&gt;
  </code></pre>
  
  <p>I Have JsonObject</p>
  
  <pre><code> var viewModel = {
              IsEnabled1 :ko.observable(true),            
              IsEnabled2 :ko.observable(true),
              IsEnabled3 :ko.observable(false)
          };
    ...
    ko.applyBindings(viewModel);
  </code></pre>
  
  <p>And I want to add global check box that will be check/uncheck all other, I made this changes on JavaScript side but global check box update UI part but they data from separate check boxes doesn't mapping to JSON object .</p>
  
  <p>Global checkbox</p>
  
  <pre><code>  $("#GeneralTable thead tr th:first input:checkbox").click(function () {
              var checkedStatus = this.checked;
              $("#GeneralTable tbody tr td:first-child input:checkbox").each(function () {
                  this.checked = checkedStatus;                    
              });
  
          });
  </code></pre>
  
  <p>after this code my JSON object contain data that not related to UI.</p>
  
  <p>How to update all JSON after change check boxes from JS side ?</p>