SF_11.0, SF_11.1, SF_11.2, SF_12.0, SF_12.1, SF_12.2, SF_13.0, SF_13.1, SF_13.2, SF_13.3, SF_14.0, SF_14.1, SF_14.2, SF_14.3 - https://docs.sitefinity.com/feather-use-content-item-selectors

DesignerView.SimpleSelector_multiple.cshtml

(function () {
    angular.module('designer').requires.push('sfSelectors');

    angular.module('designer').controller('SimpleSelectorCtrl', ['$scope', 'propertyService', function ($scope, propertyService) {
        var emptyGuid = '00000000-0000-0000-0000-000000000000';

        $scope.feedback.showLoadingIndicator = true;
        $scope.newsSelector = {
            selectedItemsIds: [],
            selectedItems: []
        };

        $scope.$watch(
            'newsSelector.selectedItemsIds',
            function (newSelectedItemsIds, oldSelectedItemsIds) {
                if (newSelectedItemsIds !== oldSelectedItemsIds) {
                    if (newSelectedItemsIds) {
                        $scope.properties.SerializedSelectedItemsIds.PropertyValue = JSON.stringify(newSelectedItemsIds);
                    }
                }
            },
            true
        );

        $scope.$watch(
            'newsSelector.selectedItems',
            function (newSelectedItems, oldSelectedItems) {
                if (newSelectedItems !== oldSelectedItems) {
                    if (newSelectedItems) {
                        $scope.properties.SerializedSelectedItems.PropertyValue = JSON.stringify(newSelectedItems);
                    }
                }
            },
            true
        );

        propertyService.get()
            .then(function (data) {
                if (data) {
                    $scope.properties = propertyService.toAssociativeArray(data.Items);
                    var selectedItemsIds = $.parseJSON($scope.properties.SerializedSelectedItemsIds.PropertyValue || null);

                    if (selectedItemsIds) {
                        $scope.newsSelector.selectedItemsIds = selectedItemsIds;
                    }
                }
            },
            function (data) {
                $scope.feedback.showError = true;
                if (data)
                    $scope.feedback.errorMessage = data.Detail;
            })
            .finally(function () {
                $scope.feedback.showLoadingIndicator = false;
            });
    }]);
})();