countries-and-timezones.js

const ct = require('countries-and-timezones')

const countries = ct.getAllCountries()

const flatten = (a) => a.reduce((acc, val) => acc.concat(val), [])

const unique = (a) => [...new Set(a)]

const combinations = Object.values(countries).map(country => {
  const { id, name } = country
  const zones = ct.getTimezonesForCountry(id)
  return zones.map(({utcOffset, offsetStr }) => {
    return {
      id,
      name,
      utcOffset,
      offsetStr
    }
  })
})

console.log(
  unique(flatten(combinations).map(c => `${c.name} (${c.offsetStr})`))
)

output.txt

[ 'Andorra (+01:00)',
  'United Arab Emirates (+04:00)',
  'Afghanistan (+04:30)',
  'Antigua & Barbuda (-04:00)',
  'Anguilla (-04:00)',
  'Albania (+01:00)',
  'Armenia (+04:00)',
  'Angola (+01:00)',
  'Antarctica (-03:00)',
  'Antarctica (+05:00)',
  'Antarctica (+07:00)',
  'Antarctica (+08:00)',
  'Antarctica (+06:00)',
  'Antarctica (+10:00)',
  'Antarctica (+03:00)',
  'Antarctica (+00:00)',
  'Antarctica (+13:00)',
  'Argentina (-03:00)',
  'Samoa (American) (-11:00)',
  'Austria (+01:00)',
  'Australia (+11:00)',
  'Australia (+10:30)',
  'Australia (+10:00)',
  'Australia (+09:30)',
  'Australia (+08:00)',
  'Australia (+08:45)',
  'Aruba (-04:00)',
  'Åland Islands (+02:00)',
  'Azerbaijan (+04:00)',
  'Bosnia & Herzegovina (+01:00)',
  'Barbados (-04:00)',
  'Bangladesh (+06:00)',
  'Belgium (+01:00)',
  'Burkina Faso (+00:00)',
  'Bulgaria (+02:00)',
  'Bahrain (+03:00)',
  'Burundi (+02:00)',
  'Benin (+01:00)',
  'St Barthelemy (-04:00)',
  'Bermuda (-04:00)',
  'Brunei (+08:00)',
  'Bolivia (-04:00)',
  'Caribbean Netherlands (-04:00)',
  'Brazil (-02:00)',
  'Brazil (-03:00)',
  'Brazil (-04:00)',
  'Brazil (-05:00)',
  'Bahamas (-05:00)',
  'Bhutan (+06:00)',
  'Botswana (+02:00)',
  'Belarus (+03:00)',
  'Belize (-06:00)',
  'Canada (-03:30)',
  'Canada (-04:00)',
  'Canada (-05:00)',
  'Canada (-06:00)',
  'Canada (-07:00)',
  'Canada (-08:00)',
  'Cocos (Keeling) Islands (+06:30)',
  'Congo (Dem. Rep.) (+02:00)',
  'Congo (Dem. Rep.) (+01:00)',
  'Central African Rep. (+01:00)',
  'Congo (Rep.) (+01:00)',
  'Switzerland (+01:00)',
  'Côte d\'Ivoire (+00:00)',
  'Cook Islands (-10:00)',
  'Chile (-03:00)',
  'Chile (-05:00)',
  'Cameroon (+01:00)',
  'China (+08:00)',
  'China (+06:00)',
  'Colombia (-05:00)',
  'Costa Rica (-06:00)',
  'Cuba (-05:00)',
  'Cape Verde (-01:00)',
  'Curacao (-04:00)',
  'Christmas Island (+07:00)',
  'Cyprus (+02:00)',
  'Czech Republic (+01:00)',
  'Germany (+01:00)',
  'Djibouti (+03:00)',
  'Denmark (+01:00)',
  'Dominica (-04:00)',
  'Dominican Republic (-04:00)',
  'Algeria (+01:00)',
  'Ecuador (-05:00)',
  'Ecuador (-06:00)',
  'Estonia (+02:00)',
  'Egypt (+02:00)',
  'Western Sahara (+00:00)',
  'Eritrea (+03:00)',
  'Spain (+01:00)',
  'Spain (+00:00)',
  'Ethiopia (+03:00)',
  'Finland (+02:00)',
  'Fiji (+12:00)',
  'Falkland Islands (-03:00)',
  'Micronesia (+10:00)',
  'Micronesia (+11:00)',
  'Faroe Islands (+00:00)',
  ... 209 more items ]