KendoGrid Aggregate

HTML

<link rel="stylesheet" href="http://cdn.kendostatic.com/2013.1.514/styles/kendo.common.min.css">
<link rel="stylesheet" href="http://cdn.kendostatic.com/2013.1.514/styles/kendo.default.min.css">
<script src="http://cdn.kendostatic.com/2013.1.514/js/kendo.all.min.js"></script>
<div id="example" class="k-content">
    <div id="grid"></div>
</div>

JavaScript

function aggregateCurrentPage(grid) {
    var columns = grid.columns;
    var data = grid.dataSource.data().toJSON();
    var totalPages = grid.dataSource.totalPages();
    var currentPage = grid.dataSource.page();
    var pageSize = grid.dataSource.pageSize();
    var aggregate = grid.dataSource.aggregate();
    var row_template = '';
    var col_template = '';
    var template_data = {};
    var template;
    var result;

    grid.element.find('tfoot').remove();
    for (var i in columns) {
        switch (columns[i].aggregate) {
            case 'count':
                var count = 0;
                if (currentPage * pageSize <= data.length) count = pageSize;
                else count = data.length % pageSize;

                template_data.count = count;
                break;
            case 'sum':
                var sum = 0;
                $.each(data, function (index, record) {
                    if (currentPage * pageSize <= data.length) {
                        if (index >= (currentPage - 1) * pageSize && index < currentPage * pageSize) {
                            sum += parseInt(record[columns[i].field]);
                        } else if (index >= currentPage * pageSize) {
                            return false;
                        } else {
                            return;
                        }
                    }
                });

                template_data.sum = sum;
                break;
            default:

        }
        col_template = columns[i].footTemplate || '&nbsp;';
        row_template += '<td>' + col_template + '</td>';
    }

    template = kendo.template('<tfoot class="k-grid-footer"><tr class="k-footer-template">' + row_template + '</tr></tfoot>');
    result = template(template_data);
    grid.element.find('table').append(result);
}

$(document).ready(function () {
    $("#grid").kendoGrid({
        dataSource: {
            type: "odata",
            transport: {
                read:...