JQuery and PHP Date difference - php

Question

I am using a jquery date picker and also setting a date through php date('Y-m-D') functions. Both of them give different date for today. Jquery picker fills the field with the date that is one day ahead of php date(). Here is the function for jquery. I need jquery to show same date for today as php.
<script type="text/javascript" charset="utf-8">
var $j = jQuery.noConflict();
$j(function()
{
// initialise the "Select date" link
$j('#date-pick')
.datePicker(
// associate the link with a date picker
{
createButton:false,
startDate: '01/01/1970',
endDate: (new Date()).asString()
//endDate:<?php echo date('y-m-d'); ?>
}
).bind(
// when the link is clicked display the date picker
'click',
function()
{
updateSelects($j(this).dpGetSelected()[0]);
$j(this).dpDisplay();
return false;
}
).bind(
// when a date is selected update the SELECTs
'dateSelected',
function(e, selectedDate, $td, state)
{
updateSelects(selectedDate);
}
).bind(
'dpClosed',
function(e, selected)
{
updateSelects(selected[0]);
}
).val(new Date().asString()).trigger('change');
var updateSelects = function (selectedDate)
{
var selectedDate = new Date(selectedDate);
if(selectedDate != "Invalid Date")
{
$j('#d').val(selectedDate.getDate());
$j('#m').val(selectedDate.getMonth()+1);
$j('#y').val(selectedDate.getFullYear());
}
}
// listen for when the selects are changed and update the picker
// default the position of the selects to today
var today = new Date();
updateSelects(today.getTime());
});
</script>

Answer 1

jQuery uses the client computer's date while php uses the server's date. They're basically different if you haven't set the default timezone in php. Take a look at this:
http://php.net/manual/en/function.date-default-timezone-set.php
You can set the default timezone in php.ini file located on the PHP main directory (Eg. PHP5.4)
As for the using of the server's date in the datepicker:
A quick google search lead me to this: how to display server side dates in jquery datepicker?
basically what they have done is creating a new date based on the current timestamp:
$timestamp = strtotime("2012-08-02");
minDate: new Date('<?php echo $timestamp; ?>');

Answer 2

DO NOT TRUST THE CLIENTS DATE AND TIME
These values can be altered at a whim.
Just use them on advisement.
Besides Javascript is there to enhance the users experience (i.e. make it more interactive). But at the end of the day you will have to pick up the pieces it you do not validate and verify the data you get from the client