Combat CORS issues in WordPress Multisite

Combat CORS issues in WordPress Multisite.php

<?php
// Make local URLs domainless, for all styles and scripts, to combat CORS issues.
// Ideally, we fix this in .htaccess using conditional headers, but in case of nginx, that's not available.

add_filter( 'script_loader_src', 'make_local_urls_domainless', 10 );
add_filter( 'style_loader_src', 'make_local_urls_domainless', 10 );

function make_local_urls_domainless( $url ) {
	global $wpdb;
	$all_domains = $wpdb->get_col( "SELECT domain FROM {$wpdb->blogs} ORDER BY blog_id DESC" );
	$all_domains_regex = implode( '|', $all_domains );
	$url = preg_replace( "@https?://(www.)?($all_domains_regex)/@i", '/', $url );

	return $url;
}