<div class="container mt-5">
        <div class="row">
            <div class="col-12 mt-5">
                <input type="date" id="yas" class="form-control">
                <button class="btn btn-success mt-5 w-100" id="tamam">Hesapla</button>
                <div id="toplam"></div>
            </div>
        </div>
    </div>
    <script>


        var tamam = document.getElementById('tamam');
        tamam.onclick = function ()
        {
            var yas = document.getElementById('yas');
            var toplam = document.getElementById('toplam');
            var date = new Date();
            var month = parseInt(date.getMonth())+1;
            var day = parseInt(date.getDate());
            var year = parseInt(date.getFullYear());
            var selectedMonth = parseInt(yas.value.substr(5,2));
            var selectedDay = parseInt(yas.value.substr(8,2));
            var selectedYear = parseInt(yas.value.substr(0,4));

            toplam.innerHTML = '';
            if (month < selectedMonth) toplam.innerHTML = (year - selectedYear)-1;
            else if (month > selectedMonth) toplam.innerHTML = year - selectedYear;
            else if (month === selectedMonth)
            {
                if (day < selectedDay) toplam.innerHTML = (year - selectedYear)-1;
                else if (day > selectedDay) toplam.innerHTML = year - selectedYear;
                else toplam.innerHTML = '🎈🎁 ' + parseInt(year - selectedYear) +' Yaşın kutlu olsun 🎈🎁';
            }
        }
    </script>