PHP and Javascript can share cookies to each other, but not able to change cookie value that created by the other.

//7 days
setcookie('tree_lang', 'ENG', time() + 7*24*60*60, "/");

$_COOKIE['tree_lang'];

Reference:

• jQuery cookie: https://github.com/carhartl/jquery-cookie
• http://www.w3schools.com/php/php_cookies.asp
• http://www.php.net/manual/en/function.setcookie.php#109173