Professional JavaScript For Web Developers

Chapter 16
The one restriction on setting cookies in PHP is that it must be done before anything is output to the
client. This is similar to the way the header() function works. For instance, this code won’t work:
To retrieve the value of a cookie in PHP, use the $_COOKIE associative array with the name of the cookie
as the key:
Note that you cannot retrieve the value of a cookie created with setcookie() until the next page loads,
meaning that is the following code is impossible:
To delete a cookie in PHP, just use the setcookie() method and set the expiration time to 0:
Passing cookies between client and server
To communicate to JavaScript, often the server creates a cookie (perhaps in a servlet or other application
running on the server) just before a response is sent out. The page that is loaded now has JavaScript
designed to retrieve the cookie value.
For example, suppose you are creating a feedback form on a Web site where the user is required to enter
a name, e-mail address, and the feedback message. You can make this more user-friendly by allowing
the users to save their names and e-mail addresses so the next time they visit and want to leave feedback,
both fields are already filled in. Typically, you do this with a Remember Me check box, as in the
following form:
Name:
E-mail Address:
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