Create HTML Select Element for Timezones

<label for="timeZone">Select Timezone</label>
<select id="timeZone">
  <?php 
    function timezone_list() {
        static $timezones = null;

        if ($timezones === null) {
            $timezones = [];
            $offsets = [];
            $now = new DateTime();

            foreach (DateTimeZone::listIdentifiers() as $timezone) {
                $now->setTimezone(new DateTimeZone($timezone));
                $offsets[] = $offset = $now->getOffset();
                $timezones[$timezone] = '(' . format_GMT_offset($offset) . ') ' . format_timezone_name($timezone);
            }

            array_multisort($offsets, $timezones);
        }

        return $timezones;
    }

    function format_GMT_offset($offset) {
        $hours = intval($offset / 3600);
        $minutes = abs(intval($offset % 3600 / 60));
        return 'GMT' . ($offset ? sprintf('%+03d:%02d', $hours, $minutes) : '');
    }

    function format_timezone_name($name) {
        $name = str_replace('/', ', ', $name);
        $name = str_replace('_', ' ', $name);
        $name = str_replace('St ', 'St. ', $name);
        return $name;
    }

    $cities = timezone_list();

    foreach($cities as $city) {
      echo '<option value='.$key.'>'.$city.'</option>';
    };
  ?>
</select>