Contao\Template::minifyHtml PHP Method

    public function minifyHtml($strHtml)
    {
        // The feature has been disabled
        if (!\Config::get('minifyMarkup') || \Config::get('debugMode')) {
            return $strHtml;
        }
        // Split the markup based on the tags that shall be preserved
        $arrChunks = preg_split('@(</?pre[^>]*>)|(</?script[^>]*>)|(</?style[^>]*>)|( ?</?textarea[^>]*>)@i', $strHtml, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
        $strHtml = '';
        $blnPreserveNext = false;
        $blnOptimizeNext = false;
        $strType = null;
        // Check for valid JavaScript types (see #7927)
        $isJavaScript = function ($strChunk) {
            $typeMatch = array();
            if (preg_match('/\\stype\\s*=\\s*(?:(?J)(["\'])\\s*(?<type>.*?)\\s*\\1|(?<type>[^\\s>]+))/i', $strChunk, $typeMatch) && !in_array(strtolower($typeMatch['type']), static::$validJavaScriptTypes)) {
                return false;
            }
            if (preg_match('/\\slanguage\\s*=\\s*(?:(?J)(["\'])\\s*(?<type>.*?)\\s*\\1|(?<type>[^\\s>]+))/i', $strChunk, $typeMatch) && !in_array('text/' . strtolower($typeMatch['type']), static::$validJavaScriptTypes)) {
                return false;
            }
            return true;
        };
        // Recombine the markup
        foreach ($arrChunks as $strChunk) {
            if (strncasecmp($strChunk, '<pre', 4) === 0 || strncasecmp(ltrim($strChunk), '<textarea', 9) === 0) {
                $blnPreserveNext = true;
            } elseif (strncasecmp($strChunk, '<script', 7) === 0) {
                if ($isJavaScript($strChunk)) {
                    $blnOptimizeNext = true;
                    $strType = 'js';
                } else {
                    $blnPreserveNext = true;
                }
            } elseif (strncasecmp($strChunk, '<style', 6) === 0) {
                $blnOptimizeNext = true;
                $strType = 'css';
            } elseif ($blnPreserveNext) {
                $blnPreserveNext = false;
            } elseif ($blnOptimizeNext) {
                $blnOptimizeNext = false;
                // Minify inline scripts
                if ($strType == 'js') {
                    $objMinify = new Minify\JS();
                    $objMinify->add($strChunk);
                    $strChunk = $objMinify->minify();
                } elseif ($strType == 'css') {
                    $objMinify = new Minify\CSS();
                    $objMinify->add($strChunk);
                    $strChunk = $objMinify->minify();
                }
            } else {
                // Remove line indentations and trailing spaces
                $strChunk = str_replace("\r", '', $strChunk);
                $strChunk = preg_replace(array('/^[\\t ]+/m', '/[\\t ]+$/m', '/\\n\\n+/'), array('', '', "\n"), $strChunk);
            }
            $strHtml .= $strChunk;
        }
        return trim($strHtml);
    }