checkinout.html

<html><head><title>Checkin-Checkout</title>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
<script>
$(document).ready( function() {
    var chin = CheckDate( new Date(), 0);
    $('#checkin').val( chin );
    var chout = CheckDate( new Date(), 1);
    $('#checkout').html( chout );

    $('#checkin,#malam').on('change', function() {
        var checkin = $('#checkin').val().split('-');
        var malam = parseInt($('#malam').val());
        var dcheckin = new Date(checkin[0], checkin[1]-1, checkin[2]);
        chout = CheckDate( dcheckin, malam);
        $('#checkout').html( chout );
    });
});

    function CheckDate(chin, malam) {
        if(chin=='Invalid Date') return '';
        chin.setDate(chin.getDate()+malam);
        var tgl = chin.getDate();
        if(tgl<10) tgl = "0"+tgl;
        var bln = chin.getMonth();
        bln++;
        if(bln<10) bln = "0"+bln;
        var thn = chin.getFullYear();
        return thn+'-'+bln+'-'+tgl;
    }
</script>
</head>
<body>
</br></br>
<center>
<form>
    Nama Lengkap :  <input type="text" name="nama"><br>
    Tipe Kamar: <select name="tipekamar" id="tipekamar">
        <option value="1">Presidential Suite</option>
        <option value="2">Suite Room</option>
        <option value="3">Junior Suite</option>
        <option value="4">Deluxe</option>
        <option value="5">Superior</option>
        <option value="6">Standard</option>
        </select><br>
    Tanggal Check In :
    <input type="date" id="checkin" name="checkin" style='font: bold 16px verdana; color:blue;'>
    &nbsp; &nbsp;Jumlah Malam : <select name="malam" id="malam" style='font: bold 16px verdana;'>
        <option value="1">1</option>
        <option value="5">5</option>
        <option value="9">9</option>
        <option value="14">14</option>
        <option value="22">22</option>
        <option value="41">41</option>
        </select>
    &nbsp; &nbsp;Checkout:
    <span id="checkout" style='font: bold 16px verdana; color:red;'></span><br>
    <!--input type="submit" value="Submit"-->
</form>
</center>
</body>
</html>