How to expire a page (no back allowed)?

yvo

Hi,

I want to do a simple thing, the user of my php web page could not use the back button.

How can I expire definively the page as soon as the user exits it.

I've seen that in a lot of internet pages.

stevesweetland

heres two handy little functions for your core code file :

function dontexpire(){
    Header("Expires: Mon, 26 Jul 2010 05:00:00 GMT");
    Header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
    Header("Cache-Control: public");
};

function expire(){
    Header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
    Header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
    Header("Cache-Control: no-cache, must-revalidate");
    Header("Pragma: no-cache");
};

then, at the top of your php program, or at least before you send any html, do this

include("myfavouritecorefile.php");
include("variousotherstuff.php");

expire();

print "foo bar";

include("myfavouritecorefile.php");
include("variousotherstuff.php");

dontexpire();

print "foo bar";

if you would like to cache the page.

actually, dontexpire() is quite handy for people who like forms. it means that you can cache a page which has been generated using a form, so if someone clicks away, then uses the back button to return to the page, shock horror, no page expiry.

QUESTION
do you want to prevent a page being cached, or prevent someone clicking the back button? the answer to your problem will be different if the latter.