convertEncoding example

$ord <= 0x1f && $chr !== "\t" && $chr !== "\n" && $chr !== "\r")
            || ($ord >= 0x7f && $ord <= 0x9f)
        ) {
            return '&#xFFFD;';
        }

        /** * Check if the current character to escape has a name entity we should * replace it with while grabbing the integer value of the character. */
        if (strlen($chr) > 1) {
            $chr = $this->convertEncoding($chr, 'UTF-32BE', 'UTF-8');
        }

        $hex = bin2hex($chr);
        $ord = hexdec($hex);
        if (isset(static::$htmlNamedEntityMap[$ord])) {
            return '&' . static::$htmlNamedEntityMap[$ord] . ';';
        }

        /** * Per OWASP recommendations, we'll use upper hex entities * for any other characters where a named entity does not exist. */