chunk.filter.js

(function() {
    'use strict';

    angular
        .module('chunkFilter')
        .filter('chunk', chunk);

    function chunk() {
        return function(value, size, vertical, preserveKeys) {
            var chunks = [];
            var chunkCount = size;
            var chunkIndex;

            if (!value || value.length === 0) {
                return value;
            }

            vertical = vertical || false;
            preserveKeys = preserveKeys || false;

            if (!vertical) {
                chunkCount = Math.ceil(value.length / size);
            }

            for (chunkIndex = 0; chunkIndex < chunkCount; chunkIndex++) {
                chunks.push([]);
            }

            chunkIndex = 0;
            value.forEach(function(value, key) {
                if (preserveKeys) {
                    chunks[chunkIndex][key] = value;
                } else {
                    chunks[chunkIndex].push(value);
                }

                if (++chunkIndex === chunkCount) {
                    chunkIndex = 0;
                }
            });

            // Hack against infdig when used in view - http://stackoverflow.com/a/29117743
            if (!value.$$splitListFilter || !angular.equals(value.$$splitListFilter, chunks)) {
                value.$$splitListFilter = chunks;
            }

            return value.$$splitListFilter;
        };
    }

})();

chunk.filter.spec.js

describe('module: chunkFilter', function() {

    beforeEach(module('chunkFilter'));

    var $filter;

    beforeEach(inject(function(_$filter_) {
        $filter = _$filter_;
    }));

    describe('filter: xcChunkFilter', function() {
        it('should chunk horizontally', function() {
            var value = [1, 2, 3, 4, 5, 6];
            var size = 2;
            var vertical = false;
            var preserveKeys = false;
            var chunks = $filter('chunk')(value, size, vertical, preserveKeys);
            expect(chunks).toEqual([
                [1, 4], [2, 5], [3, 6]
            ]);
        });

        it('should chunk vertically', function() {
            var value = [1, 2, 3, 4, 5, 6];
            var size = 2;
            var vertical = true;
            var preserveKeys = false;
            var chunks = $filter('chunk')(value, size, vertical, preserveKeys);
            expect(chunks).toEqual([
                [1, 3, 5], [2, 4, 6]
            ]);
        });
    });

});