$ watch过滤日期

Question

所以我在这里找到了这个过滤器，这个过滤器没有$ watch。

filter.js

.filter('myfilter', function ($filter, moment) {
  return function (items, from, to) {
    return $filter('filter')(items, 'name', function (v) {
      var date = moment(v);
      return date >= moment(from) && date <= moment(to);
    });
  };
})

table.html

<table class="table table-bordered table-sm">
<thead class="">
    <tr>
        <th>DAY</th>
        <th>TIME IN</th>
        <th>TIME OUT</th>
        <th>DETAILS</th>
        <th>TOTAL HOURS</th>
    </tr>
</thead>
<tbody>
    <tr ng-repeat="attendance in displayedCollection | myfilter: startDate: endDate">
        <td>{{ attendance.day | date: 'EEEE, MMM d'}}</td>
        <td>{{ attendance.timeIn | date:'h:mm a' }}</td>
        <td>{{ attendance.timeOut | date:'h:mm a'}}</td>
        <td class="text-capitalize">
            <i class="fa fa-map-marker" aria-hidden="true"></i> {{ attendance.details }}</td>
        <td>{{ attendance.totalHrs | date:'hh:mm'}} </td>
    </tr>
</tbody>
<tfoot>
    <tr>
        <td>
            <strong>Total</strong>
        </td>
        <td></td>
        <td></td>
        <td></td>
        <td>
            <strong>{{ vm.attendance.total }}</strong>
        </td>
    </tr>
</tfoot>
</table>

如何查看过滤器，因为displayedCollection.length没有变化？