Including CSS and JS in any page to head and before body tag

gistfile1.php

<?php
/*
 * Register CSS and JS to load in head of website
 */
$link = $modx->getOption('link', $scriptProperties, '');

if (empty($link)) {
    return false;
}

$links = explode(',', preg_replace('/\s+/', '', $link));

foreach ($links as $lnk) {
    list($type, $lnk) = explode('||', $lnk);

    if ($type === 'css') {
        $modx->regClientCSS($lnk);
    }

    if ($type === 'js') {
        $modx->regClientScript($lnk);
    }
}

gistfile2.txt

How to use

[[!cssJSRegister?link=`
    css||/assets/css/flexslider.css,
    js||/assets/js/jquery.flexslider-min.js,
    js||/assets/js/global.js
`]]