In my functions.php file, I added the following:
if (!is_admin()) {
add_filter('clean_url', function($url) {
if (strpos($url, '.js') === false || strpos($url, 'jquery.min.js') != false || strpos($url, 'acf') != false) {
return $url;
}
return "$url' defer='defer";
}, 11, 1);
}
The clean_url filter modifies the URL of any script being enqueued – this is where I was adding my own defer property to my scripts. However, as this was causing an issue with my ACF forms, I added an exception so that it didn’t add a defer for any ACF scripts.
If you’ve got something else that’s handling script deferment, you’ll need to check to see if it has hooks that allow you to add exceptions.
