AngularJS – groupBy filter

groupBy.js

angular.module('filters.groupBy', [])

.filter('groupBy', function() {
    return function(items, groupedBy) {
        if (items) {
            var finalItems = [],
                thisGroup;

            for (var i = 0; i < items.length; i++) {
                if (!thisGroup) {
                    thisGroup = [];
                }
                thisGroup.push(items[i]);
                if (((i+1) % groupedBy) === 0) {
                    finalItems.push(thisGroup);
                    thisGroup = null;
                }
            }

            if (thisGroup) {
                finalItems.push(thisGroup);
            }
            return finalItems;
        }
    };
});

groupBy.spec.js

describe('filter groupBy', function () {

    beforeEach(module('filters.groupBy'));

    it('should group an array', inject(function(groupByFilter) {
        expect(groupByFilter([1,2,3,4,5], 2)).toEqual([[1,2], [3,4], [5]]);
    }));
});