Problems handling cookies with javascript and PHP

[Jhorra]

On one page I add items to a cookie using javascript, then on a separate page I read them. The problem I'm having is that I can read them, but when I try to change the value of the cookie that was set with javascript.

I read the cookie $_COOKIE['rentals'], but when I try and clear that cookie using $_COOKIE['rentals'] = ""; it doesn't do anything, because on the page I'm redirecting to I echo out the value of the cookie, and it's still there. Is there an issue with setting a cookie with javascript and reading it with PHP?

[traxxas]

Cookies are sent from the client side to the server. You need to removed them from the client so they aren't sent to the server and set by PHP. If you want PHP to control the state from page to page then sessions is what you should be using.

[Jhorra]

But you can obviously read and set cookies using PHP, so if I can read it why in this case can I not set the value?

[traxxas]

Because PHP can't delete a cookie from the serverside. According to the docs:

When deleting a cookie you should assure that the expiration date is in the past, to trigger the removal mechanism in your browser.

http://us.php.net/manual/en/function.setcookie.php

[wonshikee]

You cannot write to cookies using $_COOKIE, you must use setcookie() and overwrite the old one.

[Jhorra]

Ah, thank you.

[Jhorra]

So, should this work, changing $_COOKIE['rentals'] = ""; to setcookie('rentals', ''); ?

[ahundiak]

The manual is a terrible thing to waste.

<?php
// set the expiration date to one hour ago
setcookie ("TestCookie", "", time() - 3600);
setcookie ("TestCookie", "", time() - 3600, "/~rasmus/", ".example.com", 1);
?>