Javascript 当前所选项目的角度传递索引（在选择列表中）

我正在尝试传递当前选定项的索引，以便使用它的索引深入挖掘某些嵌套数组。这是我到目前为止所拥有的

                    <select class="selectLevel1" ng-model="scope2"  ng-change='scope2Change()' 
                                ng-options='area.name for area in array2 track by area.id' >
                                </select>


                    <select class="selectLevel2" ng-model="scope3" ng-change='scope3Change()' 
                            ng-options='obj.name for obj in array3 track by obj.id' >
                    </select>

我的控制器：

$scope.scope1Change = function() {

        $scope.array3.length = 0;
        $scope.array4.length = 0;


        $scope.array2 = $scope.array[$scope.scope1].areas;

        angular.forEach($scope.array[$scope.scope1].areas, function(index) {
            angular.forEach(index.sections , function(indx){
                $scope.array3.push(indx);
            });
        });

        angular.forEach($scope.array[$scope.scope1].areas, function(tex) {
            angular.forEach(tex.sections , function(texi){

                angular.forEach(texi.lessons , function(texa){

                    $scope.array4.push(texa);

                });
            });
        });


    };

                    <select class="selectLevel1" ng-model="scope2"  ng-change='scope2Change()' 
                                ng-options='area.name for area in array2 track by area.id' >
                                </select>


                    <select class="selectLevel2" ng-model="scope3" ng-change='scope3Change()' 
                            ng-options='obj.name for obj in array3 track by obj.id' >
                    </select>

html:

                    <select class="selectLevel1" ng-model="scope2"  ng-change='scope2Change()' 
                                ng-options='area.name for area in array2 track by area.id' >
                                </select>


                    <select class="selectLevel2" ng-model="scope3" ng-change='scope3Change()' 
                            ng-options='obj.name for obj in array3 track by obj.id' >
                    </select>

                    <select class="selectLevel1" ng-model="scope2"  ng-change='scope2Change()' 
                                ng-options='area.name for area in array2 track by area.id' >
                                </select>


                    <select class="selectLevel2" ng-model="scope3" ng-change='scope3Change()' 
                            ng-options='obj.name for obj in array3 track by obj.id' >
                    </select>

因此，我需要当前所选项目的索引，以便它知道要查找哪个数组，然后填充它下面的选择列表（下面还有一些，我只是想先让它工作）。如果我硬编码括号中的一个值，比如$scope.array[0]，它可以正常工作，但我正在尝试让它动态工作。[$scope.scope1]返回完整对象，当我只是查找其索引作为数值时。有什么方法可以在角度上做到这一点？谢谢

明白了

                    <select class="selectLevel1" ng-model="scope2"  ng-change='scope2Change()' 
                                ng-options='area.name for area in array2 track by area.id' >
                                </select>


                    <select class="selectLevel2" ng-model="scope3" ng-change='scope3Change()' 
                            ng-options='obj.name for obj in array3 track by obj.id' >
                    </select>

$scope.array[$scope.array.indexOf（$scope.scope1）]

                    <select class="selectLevel1" ng-model="scope2"  ng-change='scope2Change()' 
                                ng-options='area.name for area in array2 track by area.id' >
                                </select>


                    <select class="selectLevel2" ng-model="scope3" ng-change='scope3Change()' 
                            ng-options='obj.name for obj in array3 track by obj.id' >
                    </select>