如何从ng-options下拉列表中创建自动选择所有选项的"select all“选项？

<select ng-model="selectedOptions" ng-change="toggleSelectAll()">
  <option value="all">select all</option>
  <option ng-repeat="option in options" value="{{option.value}}">{{option.label}}</option>
</select>

$scope.options = [
  { value: 'option1', label: 'Option 1' },
  { value: 'option2', label: 'Option 2' },
  { value: 'option3', label: 'Option 3' },
  // 添加更多选项...
];

$scope.selectedOptions = [];

$scope.toggleSelectAll = function() {
  if ($scope.selectedOptions.indexOf('all') !== -1) {
    // 选择了"select all"选项，将所有选项的值添加到selectedOptions数组中
    $scope.selectedOptions = $scope.options.map(function(option) {
      return option.value;
    });
  } else {
    // 取消选择了"select all"选项，清空selectedOptions数组
    $scope.selectedOptions = [];
  }
};