title: Date table column sort issue in angular js
body: <p>I am having some issue while sorting date field in table header. Sort id working properly for string and number. I have gone through <a href="http://jsfiddle.net/poppypoop/2463hsvd/" rel="nofollow">http://jsfiddle.net/poppypoop/2463hsvd/</a>. I replaced my json and tested.This is also working on basis of string.</p>
  
  <p>Js Code:</p>
  
  <pre><code>&lt;script&gt;
      var myApp = angular.module("myApp",[]);
      function myCtrl($scope){
          $scope.descending = false;
          $scope.columnToOrderBy = 'date';
          $scope.data = [
             {  
            "defaultWH":"5",
            "flowRouteName":"HIGH RISK",
            "startDate":"01/03/2016",
            "endDate":"23/03/2016",
            "hiddenStartDate":1456837200000,
            "commodityCode":"100042110",
            "commodityId":8,
            "stockingPointId":5
         },
         {  
            "defaultWH":"8",
            "flowRouteName":"HIGH RISK",
            "startDate":"25/04/2016",
            "endDate":"27/04/2016",
            "hiddenStartDate":1459864800000,
            "commodityCode":"100042110",
            "commodityId":8,
            "stockingPointId":8
         },
         {  
            "defaultWH":"8",
            "flowRouteName":"HIGH RISK",
            "startDate":"04/03/2018",
            "endDate":"20/03/2018",
            "hiddenStartDate":1520101800000,
            "commodityCode":"100042110",
            "commodityId":8,
            "stockingPointId":8
         }
          ];  
      }
  
  &lt;/script&gt;
  </code></pre>
  
  <p>Html code:</p>
  
  <pre><code>&lt;div ng-app="myApp"&gt;
      &lt;div ng-controller="myCtrl"&gt;
          &lt;table cellspacing="0" cellpadding="5" border="2"&gt;
              &lt;tr&gt;
                  &lt;th ng-click=" columnToOrderBy ='startDate'; descending = !descending"&gt;
                      Date
                  &lt;/th&gt;
                  &lt;th ng-click=" columnToOrderBy ='Location'; descending = !descending"&gt;
                      Location
                  &lt;/th&gt;
              &lt;/tr&gt;
              &lt;tr ng-repeat="item in data | orderBy:columnToOrderBy:descending"&gt;
                  &lt;td&gt;&lt;div ng-bind="item.startDate"&gt;       &lt;/div&gt;&lt;/td&gt;
                  &lt;td&gt;&lt;div ng-bind="item.flowRouteName"&gt;           &lt;/div&gt;&lt;/td&gt;
              &lt;/tr&gt;
          &lt;/table&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>This is working on basis of String not basis of date. Thanks for your help.</p>