.htaccess: How to “Specify a cache validator”?

Question

I\'m running Google PageSpeed on my site and it\'s tell me that I need to
\"Specify a cache validator.\"

The following resources are missing a cache validator. R

Answer 1

In order to "Set A Cache Validator" you need to send the following in your headers:

Expires or Cache-Control: max-age

AND

Last-Modified or ETag

So, for example, in PHP you could add the following for CSS and JS files:

    Header set Expires "Thu, 21 May 2013 20:00:00 GMT"
    Header set Last-Modified "Thu, 21 May 2012 20:00:00 GMT"

This will satisfy Google's Pagespeed calculator.