Question

I am working on a new website. While testing some of the functionality I had a number of debug statements and was watching the logs. It seems that Firefox (at least) loads the “next” page in the menu as well as the page I have clicked on. If I have menu items A B C D E and click on B then I see a request for mysite.com/B and then a request for mysite.com/C in the logs, and so on.

Is this some kind of look-ahead performance thing? Is there any way to avoid it (setting an attribute on the link maybe?) The problem is that the second page in my menu is somewhat heavier as it loads a whole lot of data from a web service. I’m happy for people to do that if they want to use the functionality, but would rather not that every visitor to the front page loads it unneccessarily. Is this behvaiour consistent across browser?

Answer 1

Yes, Firefox will prefetch links to improve the perceived performance to the user. You can read more about the functionality in Firefox here https://developer.mozilla.org/en-US/docs/Link_prefetching_FAQ

It isn’t possible to disable this in the client’s browser, however the request should include the header X-moz: prefetch which you can use to determine if it is in fact a prefetch request or not, and potentially return a blank page for prefetch requests. You can then use Cache-control: must-revalidate to make sure the page loads appropriately when actually requested by the user.

If you happen to be using Worpdress for your site, you can disable the tags with the prefetch information by using:

WordPress 3.0+

//remove auto loading rel=next post link in header
remove_action('wp_head', 'adjacent_posts_rel_link_wp_head');

Older versions:

//remove auto loading rel=next post link in header
remove_action('wp_head', 'adjacent_posts_rel_link');