Retrieving and Comparing Dates using JQuery And PHP - php

Question

I am using jQuery's datepicker in wordpress/PHP and I am using this code to show dates:
<script src="http://code.jquery.com/jquery-latest.js"></script>
<script>
$(function() {
$("#datepicker").datepicker();
$("#datepicker").datepicker("option","dateFormat",'yy-mm-dd');
});
</script>
Date<input type="text" id="datepicker" size="20" maxlength="15" style="width: 80px;" readonly="readonly"/>
It successfully displays my date.
Also, I have a table (wp_redeem_vouchers) in the database that has specific voucher redemption dates saved in it:
id wp_deal_id redeem_date
1 Amazon6767 2012-03-21
2 Ebay87nm 2013-06-12
3 M&Svouc 2013-01-01
4 ASDA 2011-09-08
Question:
How can I retrieve "redeem_date" and compare with the datepicker's textbox date (upon selection) with the date already saved in the database?
Is there anyway I could disable past date so that user can't choose the past date from date picker? i.e The user on 14/03/2013 can't choose 22/02/2013 from datepicker.

Answer 1

For your i)
$('#datepicker').datepicker( {
minDate: 0,
onSelect: function(dateText, inst) {
$.ajax({
type: "POST",
url: "some.php",
data: { date: dateText },
onSuccess: function(e){
alert("success");
}
});
});
Then in the some.php file you do your compare with mysql and you return a success or failure getting the alert(success).
Then I would start with
$date = $_POST['date'];
die($date);
In the some.php just to see if it is passed correctly.

Answer 2

Well, you can pass your datepicker date string (adjust format to $("#datepicker").datepicker("option","dateFormat",'yyyy-mm-dd');) to following JavaScript function which creates a Date object:
function createDate(s) {
var bits = s.split('-');
var d = new Date(bits[0], bits[1] - 1, bits[2]);
return d;
}
Then you have to retrieve the date value from your database.
I do not know if there is a wordpress limitation but you can trigger a Ajax-Request which reads out the database value and give you as a response the date string as a JavaScript variable.
This variable can also be passed to the createDate(date) function. With these two date objects you can call easily compare the date with the time in milliseconds -> getTime() function of date object.
Regards