Find related properties inside object

find_related.js

(function(services, _) {
    'use strict';

    services.factory('findRelated', function() {
        return findRelated;
    });
    
    function findRelated(items) {

        // items should default to an array of objects
        items = _.isArray(items) ? items : [];
        
        /**
         * Find the common properties between to objects
         * @param  {Object}     master_obj  The master object which keeps track of found commonalities
         * @param  {Object}     itr_obj     The object to compare
         * @return {Object}                 The master object
         */
        function getCommonProperties(master_obj, itr_obj) {

            // loop over the enumerable properties of master object, 
            // compare them with the current iteration obj
            _.each(master_obj, function(val, key) {

                var is_array = _.isArray(val),
                    is_non_empty_obj = _.isObject(val) && !_.isEmpty(val),
                    is_empty_obj = _.isObject(val) && _.isEmpty(val);

                if (is_array) {
                    return master_obj[key] = _.intersection(val, itr_obj[key]);
                }

                if (is_non_empty_obj) {
                    return master_obj[key] = getCommonProperties(val, itr_obj[key]);
                }

                if (is_empty_obj || itr_obj[key] !== val) {
                    delete master_obj[key];
                }

            });

            return master_obj;
        }

        // use the first element as comparator, use the rest of the list to enumerate over
        return _.reduce(_.rest(items), getCommonProperties, items[0]);
    }

})(
    window.application.services,
    window._
);