JavaScript: Adjust Date Timezone

gistfile1.js

// Inspired from http://stackoverflow.com/questions/2771609/how-to-ignore-users-time-zone-and-force-date-use-specific-time-zone
  function adjust_date_timezone(date, timezone_hours_offset, local_offset) {

    date = set_default_arg(date, new Date());

    timezone_hours_offset = !(timezone_hours_offset === null || typeof timezone_hours_offset === 'undefined') ? timezone_hours_offset: optools_settings.timezone_hours_offset;
    local_offset = !(local_offset === null || typeof local_offset === 'undefined') ? local_offset: date.getTimezoneOffset() *60*1000;

    return new Date(date.getTime() + local_offset + (timezone_hours_offset *60*60*1000));
  };