You cannot always cache resources if they contain query strings. If you proceed to remove these query strings, you will get an enhanced speed score due to more assets being cached. Static files, in particular, are highly cacheable since they are, well, not dynamic and do not change much over time.

Most proxies, Squid in particular from the first version to 3.0, make sure that some resources with a "?" in the URL are not cached by some proxy caching servers. This is true even if the response includes a Cache-control: public header.

It is essential to remove query strings from static resources as they can trigger caching problems that might not be obvious to you. To allow caching for these resources, you simply remove query strings from the references to static resources.

Then, if you still need them, you can encode the version parameters in the names of the files themselves. This way you will get the benefit of versioning and the ability to “cache bust” while avoiding any potential caching problems with your static files.

How to use Code to Remove Query Strings from Static Resources

It’s easy to remove query strings from your assets with just a couple lines of code.

All that you need:

• Admin Dashboard
• Text Editor (Sublime Text, Notepad)
• FTP client (WinSCP, FileZilla)

The procedure to remove query strings from static resources like JavaScript and CSS is as follows:

Modify your functions.php file with a short snippet of code. This code will remove query strings from the entirety of your domain-related stylesheets and scripts. You can add the following snippet to the base of your functions.php file.

You can find this file and modify it by navigating to your WordPress dashboard then Appearance > Editor. Alternatively, you can use an FTP client to modify functions.php, which is located in your current theme folder.

If you include the following code to the functions.php file of your theme, all of your scripts will tend to remove the query string version numbers at once.

																	function _remove_script_version( $src ){ $parts = explode( '?ver', $src ); return $parts[0]; } add_filter( 'script_loader_src', '_remove_script_version', 15, 1 ); add_filter( 'style_loader_src', '_remove_script_version', 15, 1 );
																

Note: If not performed properly, editing a WordPress theme's source code could damage your blog/site. Please ensure to check with a developer before anything if you are not comfortable doing this.

Also, this code may trigger 500 internal server errors in some instances (depending on the WordPress setup that you use). It’s always recommended to back up your WordPress before taking this step.

Remove Query String from Static Resources With the Use of a Plugin

Another option if you do not want to use code is the use of a plugin for WordPress that efficiently incorporates this function. To remove query strings from static resources with a plugin, we will share a few good plugins that offer this feature.

We always suggest that you use plugins only when it becomes inevitable to use them, though it is up to you whether to use custom PHP or go with a plugin.

Remove Query Strings from Static Resources