Remove a query string added to Wordpress URLs

Question

I have to work with a Wordpress installation that wasn't mine, and I need to work out some things to optimize performance.

Among other things, I've found that almost every single URL, specially for static files, is appended with a query string, and it's always the same:

And so on.

Does anybody know a plugin that can be causing this? I have the following installed, and i can't find the one causing it or if it's something else:

Advanced Custom Fields
Akismet
Category Post Widget
Contact Form 7
Envato WordPress Toolkit
Forms: 3rd-Party Integration
Google XML Sitemaps
LayerSlider WP
Ready! Backup
Ready! Backup PRO
Redirection
Remove query strings from static resources
Special Recent Posts FREE Edition
Twoot ToolKit
W3 Total Cache
Wickett Twitter Widget
WordPress-to-Lead for Salesforce CRM
WordPress HTTPS
WordPress SEO
WP-PageNavi

score 4 · Answer 1 · answered Jun 26 '15 at 17:48

You can remove query strings from theme resources (css and javascript files) with this in your theme's functions.php file:

// Remove Query Strings from enqueue scripts
add_filter( 'style_loader_src', 'remove_query_string' );
add_filter( 'script_loader_src', 'remove_query_string' );
function remove_query_string( $url )
{
    return remove_query_arg( 'ver', $url );
}

As for query strings from plugins, I assume that will be a similar fix in each plugin.

score 3 · Accepted Answer · edited May 23 '17 at 11:52

Appending a version number as a URL query string is a common cache-busting solution.

It looks like W3 Total Cache may be the culprit here. Their website says that one of the features is:

Browser caching using cache-control, future expire headers and entity tags (ETag) with "cache-busting"

According to the author of the plugin, you can disable this feature:

Uncheck the "Prevent caching of objects after settings change" option on the browser cache settings tab.

Remove a query string added to Wordpress URLs

2 Answers2