Question

My site had a problem in that certain browsers (especially opera and gecko) were “over-caching” (caching far too much for my taste).

I’ve just added the following PHP snippet to hopefully disable caching in all browsers:

<?php 
header("Expires: Tue, 01 Jan 2000 00:00:00 GMT");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");
?>

Question: How would you test this out, to make sure it actually works?

Additions, Notes: I need a stupidly simple test; my skill level is pretty low. I can’t do cache busting (url changes) because it’s a one-page site.

Answer 1

Get the current time() and store it in the PHP session. Use var_dump() to print out the $_SESSION array, and also to print the current time(). Click “refresh” a few times. Expect the session array to remain stable and the current time to change. If both remain stable, the script output is being cached.

Example here: http://www.laprbass.com/RAY_cache_test.php

<?php // RAY_cache_test.php
error_reporting(E_ALL);
date_default_timezone_set('America/Chicago');

// SEND HEADERS
header("Expires: Tue, 01 Jan 2000 00:00:00 GMT");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");

// START SESSION
session_start();

// GET CURRENT TIME
$now = date('c');

// IF NO TIME IN SESSION YET, STORE ONE
if (!isset($_SESSION['myTest'])) $_SESSION['myTest'] = $now;

// SHOW THE SESSION AND THE CURRENT TIME
echo 'SESSION TIME: ' . $_SESSION['myTest'];
echo '<br/>';
echo 'CURRENT TIME: ' . $now;