Client.js

app.factory('Client', function() {
  function Client(obj) {
    obj.created = new Date(obj.created);
    angular.extend(this, obj);
  }
  
  return Client;
});

toDate.js

$http.get(URL).then(function(response) {
  $scope.clients = response.data.map(function(client) {
    return new Client(client);
  });
});