how to remove query strings from static resources in WordPress

Understanding Query Strings in WordPress

Query strings are a part of the URL that contain data following a question mark (?). In WordPress, static resources like JavaScript and CSS files often have query strings that indicate their version, such as style.css?ver=4.7. Although useful for version control and caching, they can negatively impact resource caching on some proxy servers and may affect the loading speed of a website.

Why Remove Query Strings

Removing query strings from URLs of static resources can enhance cacheability on proxy servers like Varnish or CDNs (Content Delivery Networks) that may not cache resources with query strings. This affects website speed and performance, crucial factors in user experience and SEO rankings.

Using Plugins to Remove Query Strings

One of the simplest methods for WordPress users is to utilize plugins. Plugins like Remove Query Strings from Static Resources, W3 Total Cache, and WP Rocket provide an easy way to handle query strings efficiently.

Remove Query Strings From Static Resources

This lightweight plugin strips the version query strings from static resources, improving your GTMetrix scores. After installing and activating, it works automatically without any settings.

W3 Total Cache

A more robust solution, W3 Total Cache offers various performance optimizations including the removal of query strings. To enable the feature:

1. Install and activate W3 Total Cache.
2. Go to Performance > Browser Cache.
3. Enable the ‘Prevent caching of objects after settings change’ option.
4. Save the settings and clear the cache.

WP Rocket

WP Rocket simplifies the process significantly:

1. Install and activate WP Rocket.
2. Navigate to the Static Files tab.
3. Under the Basic Settings, check the box next to “Remove Query Strings”.
4. Save changes and clear the cache.

Manual Method via Functions.php

For those who prefer not to use a plugin, modifying the functions.php file of your theme is an alternative approach. Insert the following code at the end of your functions.php file:

function remove_css_js_ver($src) {
    if (strpos($src, '?ver='))
        $src = remove_query_arg('ver', $src);
    return $src;
}
add_filter('style_loader_src', 'remove_css_js_ver', 10, 2);
add_filter('script_loader_src', 'remove_css_js_ver', 10, 2);

This snippet checks each script and stylesheet for a version number and removes the version query string. Note that changes made to the functions.php file can be lost when updating the theme. To avoid this, use a child theme or a custom plugin to add custom code.

Using HTAccess to Redirect Query Strings

Another method involves modifying the .htaccess file in your WordPress site’s root directory. This method is advisable only for advanced users familiar with server configurations as incorrect settings can break your site access. Add the following lines at the end of your .htaccess file:

RewriteEngine On
RewriteCond %{QUERY_STRING} "ver"
RewriteRule ^(.*)$ /$1? [R=301,L]

This code permanently redirects URLs with query strings by stripping them off, thus possibly improving caching behavior. However, it doesn’t stop WordPress from generating URLs with query strings.

Monitoring & Testing Results

After implementing any of the above methods, monitoring and testing are essential. Use tools like Google PageSpeed Insights, GTMetrix, or Pingdom to assess the impact on loading times and resource caching. Regularly checking these metrics helps understand how each change affects overall site performance.

Best Practices

• Backup: Always backup your website before making changes to critical files like .htaccess or functions.php.
• Test Compatibility: Check compatibility especially when using plugins, as they may conflict with existing plugins or the active WordPress theme.
• Updating: Be mindful of updates to WordPress, themes, or plugins which might reintroduce query strings or affect the existing modifications.

By methodically removing query strings from static resources, WordPress site owners can see a notable improvement in site speed and performance, contributing positively to SEO efforts and user experience.