Example: European countries

Set onlyCountries option to just European country codes.

Markup

<input id="phone" type="tel">

Code

var input = document.querySelector("#phone");
window.intlTelInput(input, {
  onlyCountries: ["al", "ad", "at", "by", "be", "ba", "bg", "hr", "cz", "dk",
  "ee", "fo", "fi", "fr", "de", "gi", "gr", "va", "hu", "is", "ie", "it", "lv",
  "li", "lt", "lu", "mk", "mt", "md", "mc", "me", "nl", "no", "pl", "pt", "ro",
  "ru", "sm", "rs", "sk", "si", "es", "se", "ch", "ua", "gb"],
  utilsScript: "../../build/js/utils.js?1541153396801" // just for formatting/placeholders etc
});

Result