Test to see which calendars are supported
Include the Unicode extension for setting the calendar in the locale. Display the locale used, then format the date using that locale.
by David Storey
JavaScript
console.clear();
var date = new Date(),
calendars = ["buddhist", "chinese", "coptic", "dangi", "ethioaa", "ethiopic-amete-alem", "ethiopic", "gregory", "hebrew", "indian", "islamic", "islamicc", "islamic-civil", "iso8601", "japanese", "persian", "roc"];
for (var i = 0; i < calendars.length; i++) {
var localeDate = new Intl.DateTimeFormat("en-GB-u-ca-" + calendars[i], date);
console.log(localeDate.resolvedOptions().locale + ":\t\t" + localeDate.format());
}