title: Swap 2 items in observableArray - knockout
body: <p>im tring to Replace between 2 items in observableArray with knockout  but something is wrong..</p>
  
  <p>after the replace of the items ,i will change and send the displayOrder property (in both itmems) to the server (or should i take other approach for this)</p>
  
  <pre><code>        ReplaceBetweenTwoitemsInArray: function () {
              console.log("ranking down msg");
              var currentItemindex = viewModel.myobservableArray.indexOf(this); 
              var nextItemIndex = currentItemindex + 1;
              viewModel.myobservableArray .replace(
                   viewModel.myobservableArray ()[nextItemIndex], 
                  viewModel.myobservableArray ()[currentItemindex]
               );
  
          }
  </code></pre>
  
  <p>only the first item changed to the second item but the second item doesnt become the first one</p>