How to Safely Remove the Compromised Polyfill.io Script and WordPress Polyfill Scripts
Ensuring the security and performance of your WordPress site is crucial, especially given recent security concerns such as the Polyfill.io incident. Polyfill.io, a service that delivered polyfills dynamically to ensure cross-browser compatibility, was compromised in 2024 following a change in ownership, leading to the distribution of malicious code. This incident highlights the risks of relying on third-party services for critical site functionality. Additionally, WordPress includes default scripts like regenerator-runtime and wp-polyfill to support compatibility with older browsers, which might not be necessary if your audience predominantly uses modern browsers. In this tutorial, you will learn how to remove both the compromised Polyfill.io script and the potentially unnecessary WordPress polyfill scripts to boost your site’s security and performance.
Differentiating Between Polyfill.io and WordPress’s wp-polyfill.min.js
It’s crucial to distinguish between the compromised Polyfill.io service and the wp-polyfill.min.js script that is part of WordPress. The wp-polyfill.min.js script is a safe, core part of WordPress designed to ensure modern JavaScript features work in older browsers. However, depending on your site’s audience, this script might no longer be necessary, especially if you’re not targeting older browsers like Internet Explorer 11.
Understanding the WordPress Polyfill Scripts: regenerator-runtime and wp-polyfill
Before proceeding with script removal, it’s essential to understand what regenerator-runtime and wp-polyfill do and their relevance to your site.
What is regenerator-runtime?
regenerator-runtime is a script that supports modern JavaScript features like async and await, which were introduced in ECMAScript 2017 (ES8). These features make asynchronous code easier to manage and understand. However, async and await are not supported by older browsers like Internet Explorer 11, which is why WordPress includes this script.
- Browser Relevance: This script is essential for ensuring that
asyncandawaitwork in browsers that do not natively support them. It is particularly relevant for Internet Explorer 11 and older versions of Microsoft Edge. Browsers such as Chrome (from version 55+), Firefox (from version 52+), and Safari (from version 10.1+) natively support these features, soregenerator-runtimeis not needed.
What is wp-polyfill?
wp-polyfill is a collection of polyfills included in WordPress to ensure that modern JavaScript features are compatible with older browsers. These polyfills cover a range of features like Promises, Object.assign, and other modern functionalities that older browsers lack.
- Browser Relevance:
wp-polyfillis particularly necessary for supporting older browsers like Internet Explorer 11. However, with the decline in the usage of such browsers, numerous modern websites may no longer need to load this script.
Why Consider Removing These Scripts?
If your website’s audience primarily uses modern browsers, loading regenerator-runtime and wp-polyfill may be unnecessary. By removing these scripts, you can reduce the number of HTTP requests and decrease your site’s overall JavaScript payload, leading to faster load times and improved performance. However, it’s crucial to ensure that your site does not rely on these scripts for any critical functionality before removing them.
How to Remove the WordPress Polyfill Scripts
To remove regenerator-runtime and wp-polyfill from your WordPress site, you can deregister these scripts using the following code snippet. Add this code to your child theme’s functions.php file. This snippet will ensure that the regenerator-runtime and wp-polyfill scripts are not enqueued on your site, improving both security and performance by eliminating potentially unnecessary scripts.
function remove_unnecessary_scripts() {
// Deregister regenerator-runtime script.
wp_deregister_script( 'regenerator-runtime' );
// Deregister wp-polyfill script.
wp_deregister_script( 'wp-polyfill' );
}
add_action( 'wp_enqueue_scripts', 'remove_unnecessary_scripts', 100 );
Code language: PHP (php)
Explanation:
- Deregistering
regenerator-runtime: Thewp_deregister_script('regenerator-runtime');function call ensures that theregenerator-runtimescript is not loaded on your site. Removing this script means thatasyncandawaitwill no longer be supported in older browsers like Internet Explorer 11. If your site doesn’t rely on these features, this can improve your site’s performance. - Deregistering
wp-polyfill: Thewp_deregister_script('wp-polyfill');function removes thewp-polyfillscript from being loaded. By doing so, modern JavaScript features will not be polyfilled for older browsers. This step should be taken with caution, as some themes or plugins may rely on these polyfills for functionality. - Hooking into
wp_enqueue_scripts: Theadd_action('wp_enqueue_scripts', 'remove_unnecessary_scripts', 100);function ensures that these scripts are deregistered during the script enqueueing process, with a priority of100to ensure they are removed after other scripts have been enqueued.
Identifying and Removing the Polyfill.io Script
If your site was using the Polyfill.io service, it is crucial to remove it to avoid potential security risks. Here’s how to identify and remove the Polyfill.io script:
- Checking for Polyfill.io:
View your site’s source code by right-clicking on any page and selecting “View Page Source.” Search for script tags that referencepolyfill.io. If you find a reference to this service, it indicates that your site is using the compromised script. - Removing Polyfill.io:
If the script is enqueued in your theme’sfunctions.phpfile, locate the function and remove it. Here’s an example of how to dequeue and remove the script:
// Remove the Polyfill.io script.
function remove_polyfill_io_script() {
wp_dequeue_script( 'polyfill-io' );
}
add_action( 'wp_enqueue_scripts', 'remove_polyfill_io_script', 100 );
Code language: PHP (php)
This code snippet ensures that the Polyfill.io script is no longer loaded on your WordPress site.
If the script is hard-coded into a template file, such as header.php, simply delete the script tag.
- Verifying the Removal:
After making these changes, refresh your site and utilize the browser’s Developer Tools to verify that the Polyfill.io script is no longer being loaded. Navigate to the “Network” tab in Developer Tools and check the list of loaded scripts.
That’s it! By removing the compromised Polyfill.io script and the WordPress polyfill scripts like regenerator-runtime and wp-polyfill, you can enhance your WordPress site’s security and performance. Regularly auditing the scripts that load on your site is crucial for maintaining a fast, secure, and efficient website. While these scripts are valuable for ensuring compatibility with older browsers, they might not be necessary for every website. Carefully assess your site’s requirements before removing any scripts to ensure that your site continues to function smoothly.