window.onload = function () {
    var sStartbtn = document.getElementById("shiftStart");
    if (sStartbtn) {
        sStartbtn.addEventListener("click", () => {
            let shiftStart = sStartbtn.value;
            $.post('ajax.php', {
                shiftStart: shiftStart
            }, (response) => {
                location.reload();
            });
        });
    }
    var sEndbtn = document.getElementById("shiftEnd");
    if (sEndbtn) {
        sEndbtn.addEventListener("click", () => {
            let shiftEnd = sEndbtn.value;
            $.post('ajax.php', {
                shiftEnd: shiftEnd
            }, (response) => {
                location.reload();
            });
        });
    }
}