How can Pass the value given in datetime column into the function FillHolidayPerYear var href before DN

In my code

<div class="controls col-sm-9">
<div class='input-group date' id='ToDatePicker'>
<input type='text' asp-for="ToDate" class="form-control" onchange="calculateNetHours()" />
<span class="input-group-addon">
<span class="glyphicon glyphicon-calendar"></span>
</span>
</div>
</div>

function FillHolidayPerYear() {
var href = '/Employee/HolidayPlanner? DN=' + $("#dropdownDepot option:selected").val() + '&DPT=' + $("#dropdownDepartment option:selected").val() + '&EMP=' + $("#dropdownEmployee option:selected").val();
$("#lnkFilter").attr('href', href);
$("#lnkFilter").click();
}

Please can you advise me with suggested code to bring the datetime value into the argument before DN in href = '/Employee/HolidayPlanner? DN