从jquery datepicker获取包含日期的php变量

I have a jquery datepicker defined like this :

HTML/php:

<input id="datepicker" name="date" placeholder="Date" />

Javascript:

<script>
    $(document).ready(function() {
    $("#datepicker").datepicker();
    });
</script>

This works perfectly but i need to get the date in a php variable. I tried $_POST["date"] but this does not work. Could you help me ? Thanks !

The problem is solved, I don't really know where the problem came from. I still use $_POST["date"] to get the date, then I convert it from dd/mm/yyyy to yyyy-mm-dd (because my sql request requires this format) and it works.. Anyway, thanks everyone !