Date Validation, How to validate entered date with current date

So I would like my date picker to be validated, giving the user a error script if they pick a day that exceeds the current day. In other words, they must only be able to enter a date that has not yet occured. This is my script:

<script type="text/javascript">
function checkForm(form)
{
var from_hour = document.getElementById('from_hour').value;
var from_minute = document.getElementById('from_minute').value;
var to_hour = document.getElementById('to_hour').value;
var to_minute = document.getElementById('to_minute').value;
if (from_hour > to_hour) {
alert('"From: H:"field cannot be larger than "To: H:" field');
return false;
} else if (from_hour === to_hour) {
if (from_minute > to_minute) {
alert('"From: M:"field cannot be larger than "To: M:" field');
return false;
}


}


}

</script>
<legend>Time Log</legend>
<form name="form" method="post" action="" onsubmit="return checkForm(this)" >
<table>

<tr>
<td>Date:</td>
<td><input type="text" required name="date" id="date" /></td>
<script>
$('#date').datepicker({dateFormat: "dd/mm/yy"});</script>


</td> </tr>

If you want to disable past date as well as current date you can use following statement-


$('#date').datepicker({minDate:1,dateFormat: "dd/mm/yy"});

Above statement will allow user to choose future date only