Add nonce to script and styles on WordPress

nonce.php

add_action( 'template_redirect', function () {

	ob_start( function ( $output ) {

		$nonces = [];

		$output = preg_replace_callback( '#<script.*?\>#', function ( $matches ) use ( &$nonces ) {
			$nonce = wp_create_nonce( $matches[0] );
			$nonces[] = $nonce;

			return str_replace( '<script', "<script nonce='{$nonce}'", $matches[0] );
		}, $output );
		
		$output = preg_replace_callback( '#<style.*?\>#', function ( $matches ) use ( &$nonces ) {
			$nonce = wp_create_nonce( $matches[0] );
			$nonces[] = $nonce;

			return str_replace( '<style', "<style nonce='{$nonce}'", $matches[0] );
		}, $output );

		$nonces_csp = array_reduce( $nonces, function ( $header, $nonce ) {
			return "{$header} 'nonce-{$nonce}'";
		}, '' );

		header( sprintf( "Content-Security-Policy: base-uri 'self'; form-action 'self'; object-src 'none'; script-src https:%s 'strict-dynamic'", $nonces_csp ) );

		return $output;
	} );

} );