localize and internationalize times including testing for desired result for valid times

timezone

/* samples LTR and RTL; Persian, Hebrew, Arabic, Thai, English forms, Korean, Chinese, Japanese:
"11/2/2018, 12:03:27 PM PDT"
"02/11/2018, 12:03:27 GMT-7"
"2018. 11. 2. 오후 12시 3분 27초 GMT-7"
"٢‏/١١‏/٢٠١٨ ١٢:٠٣:٢٧ م غرينتش-٧"
"2018/11/2 GMT-7 下午12:03:27"
"۱۳۹۷/۸/۱۱،‏ ۱۲:۰۳:۲۷ (‎−۷ گرینویچ)"
"30/11/2 12:03:27 GMT-7"
"2/11/2018 12.03.27 GMT-7"
"2.11.2018, 12:03:27 GMT-7‎"
"2.11.2018, 12:03:27 GMT-7"
"๒/๑๑/๒๕๖๑ ๑๒ นาฬิกา ๐๓ นาที ๒๗ วินาที GMT-๗"
*/
const date = new Date();
const time = date.toLocaleString(false, {year:'numeric',month:'numeric',day:'numeric', hour:'2-digit',minute:'2-digit', second:'2-digit', timeZoneName:'short’});
console.log(time);
// time.match(/(\p{Number}+)/ug); only works in Node v10+ Chrome etc
const nums = time.match(/[0-9\u0660-\u0669\u06F0-\u06F9\u07C0-\u07C9\u0966-\u096F\u09E6-\u09EF\u0A66-\u0A6F\u0AE6-\u0AEF\u0B66-\u0B6F\u0BE6-\u0BEF\u0C66-\u0C6F\u0CE6-\u0CEF\u0D66-\u0D6F\u0DE6-\u0DEF\u0E50-\u0E59\u0ED0-\u0ED9\u0F20-\u0F29\u1040-\u1049\u1090-\u1099\u17E0-\u17E9\u1810-\u1819\u1946-\u194F\u19D0-\u19D9\u1A80-\u1A89\u1A90-\u1A99\u1B50-\u1B59\u1BB0-\u1BB9\u1C40-\u1C49\u1C50-\u1C59\uA620-\uA629\uA8D0-\uA8D9\uA900-\uA909\uA9D0-\uA9D9\uA9F0-\uA9F9\uAA50-\uAA59\uABF0-\uABF9\uFF10-\uFF19]+/g) || [];
// any/all languages with the above options come back with 6 numbers with separating punctuation, 7 in the case of a timezone offset, like NN/NN/NN TT:TT:TT Z
console.assert(nums.length >= 6).to.equal(true);


export const formatTimeConfig = {year:'numeric',month:'numeric',day:'numeric', hour:'2-digit',minute:'2-digit', second:'2-digit', timeZoneName:'short'};
// format the time locally based on the client's browser settings
// note the fall-through for invalid falsy time values so they don't resolve to the epoch
export const formatTime = (time, config=formatTimeConfig) => {
  const when = new Date(time || '~');
  return !isNaN(when) ? when.toLocaleString(false, config) : '';
};