Asyn & Defer scripts

async_defer.php

/**
 * Add possibility to asynchroniously load javascript files
 *
 * Filters all URL strings called in clean_url() for the #asyncload value
 * and replaces said string with async='async'
 *
 * @param string $url The URL for the script resource.
 * @returns string Modified script string
 */
add_filter('clean_url', 'add_async_forscript', 11, 1);
function add_async_forscript( $url ){

    if ( strpos( $url, '#asyncload' ) === false ){
        return $url;
    } elseif ( is_admin() ){
        return str_replace( '#asyncload', '', $url );
    } else {
        return trim( str_replace( '#asyncload', '', $url ) ) . "' async='async";
    }

}

/**
 * Add possibility to Defer load javascript files
 *
 * Filters all URL strings called in clean_url() for the #deferload value
 * and replaces said string with defer='defer'
 *
 * @param string $url The URL for the script resource.
 * @returns string Modified script string
 */
add_filter('clean_url', 'add_defer_forscript', 11, 1);
function add_defer_forscript( $url ){

	if ( strpos( $url, '#deferload' ) === false ){
        return $url;
    } elseif ( is_admin() ){
        return str_replace( '#deferload', '', $url );
    } else {
        return trim( str_replace( '#deferload', '', $url ) ) . "' defer='defer";
    }

}