<input class="form-control" onchange="cal()" placeholder="Choose Date "  type="text" id="example1" name="startdate" required="required" "/>
<input class="form-control" onchange="cal()" placeholder="Choose Date "  type="text" id="example2" name="enddate" required="required" disabled="disabled" "/>
<input class="form-control"  type="text"  id="numdays2" name="total_leave"/>

<!--calendar Java script -->
<script type="text/javascript">
$(document).ready(function () {
    $('#example1').datePicker({
        format: "yyyy-mm-dd"
    });
});
</script>

<!-- Datepicker -->
<script type="text/javascript">
$(document).ready(function () {
    $('#example2').datePicker({
        format: "yyyy-mm-dd"
    });
});
</script>

<!-- calculate leave total day -->
<script type="text/javascript">
function GetDays(){
    var dropdt = new Date(document.getElementById("example2").value);
    var pickdt = new Date(document.getElementById("example1").value);
    return parseInt((dropdt -(pickdt)) / (24 * 3600 * 1000))+1|| parseInt(1);
}

function cal(){
    if(document.getElementById("example1")){
        document.getElementById("numdays2").value=GetDays();
    }
}

</script>