Detailed docs and example usage can be found
here.
Browser compatibility
The week-info fallback requires Intl.Locale. It uses native getWeekInfo() or the legacy
weekInfo getter when available, otherwise Unicode CLDR 48 regional data. It does not modify
Intl.Locale.prototype.
Unicode data license
The week-info fallback includes Unicode CLDR 48 data. See
third-party notices for its license.