JQuery UI Datepicker SetDate

I use the popular JQuery UI Datepicker to add/modify events on my web site. I am having a problem with getting the date to show up right using setDate. The incorrect date seems to always show up no matter what I do. Here are some various things I have tried:

The date shows up as 01/17/1970 when it should be 10/15/2015, this is how I need it to work, with the php:

    $(function() {
        var date = new Date(<?php echo strtotime($date); ?>);
        $("#date").datepicker();
        $("#date").datepicker("setDate", date);
        $("#date").datepicker( "option", "showAnim", "slideDown" );
    });

The date has inconsistent values when done like this, the date will always be wrong no matter what date you set, but there is no pattern.

    $(function() {
        var date = new Date(2015, 10, 15);
        $("#date").datepicker();
        $("#date").datepicker("setDate", date);
        $("#date").datepicker( "option", "showAnim", "slideDown" );
    });

I had also tried it like this previously, but forgot to put quotation marks around the php. Now it works:

<script>
    $(function() {
        $("#date").datepicker();
        $("#date").datepicker("setDate", "<?php echo $date ?>");
        $("#date").datepicker( "option", "showAnim", "slideDown" );
    });
</script>

The Javascript Date object's constructor takes milliseconds when given only one argument.

The PHP function strtotime() returns the Unix Timestamp, the number of seconds since 1970-01-01.

If you multiply the timestamp by 1,000, you'll get a suitable value to pass to the Date constructor.

var date = new Date(<?php echo (strtotime($date) * 1000); ?>);