$('#WeekFrom').change(function () {

    var selectedValue = $('#WeekFrom').val();
    $.post(ajaxSetWeekFrom, { data: selectedValue });
});

$(document).ready(function () {
    $('#btn-week-from').click(function () {
        var selectedValue = $('#WeekFrom').val();
        $.post(ajaxSetWeekFrom, { data: selectedValue });
    });
});