Javascript 引导计时器中的验证

我正在使用AngularUI引导时间选择器

        <button type="button" class="btn btn-default dropdown-toggle" ng-click="openStartTime($event, 'time')">
            <i class="glyphicon glyphicon-time"></i>
        </button>
        <div dropdown is-open="timepickerOpened1">
          <span class="dropdown-menu" role="menu">
              <timepicker ng-model="meetingInfo.startTime" ng-change="changed()"  show-meridian="true"></timepicker>
          </span>
        </div>

        <button type="button" class="btn btn-default dropdown-toggle" ng-click="openEndTime($event, 'time')">
            <i class="glyphicon glyphicon-time"></i>
        </button>
        <div dropdown is-open="timepickerOpened2">
          <span class="timePickerCls dropdown-menu" role="menu">
              <timepicker  ng-model="meetingInfo.endTime" ng-change="changed()" show-meridian="true"></timepicker>
          </span>
        </div>

开始时间代码

        <button type="button" class="btn btn-default dropdown-toggle" ng-click="openStartTime($event, 'time')">
            <i class="glyphicon glyphicon-time"></i>
        </button>
        <div dropdown is-open="timepickerOpened1">
          <span class="dropdown-menu" role="menu">
              <timepicker ng-model="meetingInfo.startTime" ng-change="changed()"  show-meridian="true"></timepicker>
          </span>
        </div>

        <button type="button" class="btn btn-default dropdown-toggle" ng-click="openEndTime($event, 'time')">
            <i class="glyphicon glyphicon-time"></i>
        </button>
        <div dropdown is-open="timepickerOpened2">
          <span class="timePickerCls dropdown-menu" role="menu">
              <timepicker  ng-model="meetingInfo.endTime" ng-change="changed()" show-meridian="true"></timepicker>
          </span>
        </div>

        <button type="button" class="btn btn-default dropdown-toggle" ng-click="openStartTime($event, 'time')">
            <i class="glyphicon glyphicon-time"></i>
        </button>
        <div dropdown is-open="timepickerOpened1">
          <span class="dropdown-menu" role="menu">
              <timepicker ng-model="meetingInfo.startTime" ng-change="changed()"  show-meridian="true"></timepicker>
          </span>
        </div>

        <button type="button" class="btn btn-default dropdown-toggle" ng-click="openEndTime($event, 'time')">
            <i class="glyphicon glyphicon-time"></i>
        </button>
        <div dropdown is-open="timepickerOpened2">
          <span class="timePickerCls dropdown-menu" role="menu">
              <timepicker  ng-model="meetingInfo.endTime" ng-change="changed()" show-meridian="true"></timepicker>
          </span>
        </div>

---

我的问题：如何添加验证以检查输入的结束时间是否总是大于开始时间？谢谢您可以添加语句来更改函数，如

        <button type="button" class="btn btn-default dropdown-toggle" ng-click="openStartTime($event, 'time')">
            <i class="glyphicon glyphicon-time"></i>
        </button>
        <div dropdown is-open="timepickerOpened1">
          <span class="dropdown-menu" role="menu">
              <timepicker ng-model="meetingInfo.startTime" ng-change="changed()"  show-meridian="true"></timepicker>
          </span>
        </div>

        <button type="button" class="btn btn-default dropdown-toggle" ng-click="openEndTime($event, 'time')">
            <i class="glyphicon glyphicon-time"></i>
        </button>
        <div dropdown is-open="timepickerOpened2">
          <span class="timePickerCls dropdown-menu" role="menu">
              <timepicker  ng-model="meetingInfo.endTime" ng-change="changed()" show-meridian="true"></timepicker>
          </span>
        </div>

   if ($scope.end <= $scope.start) {

      $scope.end = new Date($scope.start.getTime() + $scope.mstep * 60000)


    }

---

if（$scope.end谢谢@sylvester.Well explained！！