Getting undefined error when posting data to controller.How ?

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MVC

jQuery

for (var i = 0; i < _checkedData.length; i++) {
document.getElementById('testcheck').value = document.getElementById('testcheck').value + '!' + _checkedData[i];
}

$.ajax({
            url: '/COCS/ISI/COCSIntimation/AuthorizeSubmit' + "&checkeddata=" + document.getElementById('testcheck').value,
            data: _checkedData,
            type: 'POST',
            contentType: 'application/json; charset=utf-8',

success: function (result) {
                $('#grid').data('kendoGrid').dataSource.data(result);
            },
            dataType: 'json'
        });

$(function () {
$('#grid').on('click', '.chkbxAuthorize', function () {
var checked = $(this).is(':checked');
var grid = $('#grid').data().kendoGrid;
var dataItem = grid.dataItem($(this).closest('tr'));


//var grid = $("#grid").data("kendoGrid");
var data = grid.dataSource.data();
//var checked = $(this).is(':checked');
//var dataItem = grid.dataItem($(this).closest('tr'));

var totalRows = $("#grid td :checkbox").length;
var AuthChecked = $(".chkbxAuthorize:checked").length;

if (checked) {
_checkedData.push(dataItem);
}
});


<input type="hidden" id="testcheck" value="" name="hdn">