formatTime for Asia/Kolkata and FunPlanat/moon gives always the same result

Question

i got the same result (the correct time for Latvia) when using the following EcmaScript6 Source

in 0 A.D.

In the case of 0 A.D. that is used here, the game's source code include JavaScript code written using ES6 syntax. This code would be executed by a JavaScript engine that is bundled with the game's runtime environment. BTW there is no support for console.log()

const formatTime = (date, timeZone) => {
  const options = {
    hour: "numeric",
    minute: "numeric",
    hour12: true,
    timeZone: timeZone,
  };
  return date.toLocaleTimeString("en-US", options);
};

const getNextHalfHour = (inNextFullMinute) => {
  const now = new Date();
  const minutes = now.getMinutes();

  if (!inNextFullMinute && isNaN(inNextFullMinute)) inNextFullMinute = 30;
  else inNextFullMinute = parseInt(inNextFullMinute);

  const roundedMinutes =
    Math.ceil(minutes / inNextFullMinute) * inNextFullMinute;
  const nextHalfHour = new Date(
    now.getFullYear(),
    now.getMonth(),
    now.getDate(),
    now.getHours(),
    roundedMinutes,
    0,
  );
  if (roundedMinutes === 60) {
    nextHalfHour.setHours(now.getHours() + 1);
    nextHalfHour.setMinutes(0);
  }
  return nextHalfHour;
};

const nextHalfHour = getNextHalfHour();
console.log(
  "Europe/London:",
  formatTime(
    new Date(nextHalfHour.getTime() + 1 * 60 * 60 * 1000),
    "Europe/London",
  ),
);

console.log(
  "America/Los_Angeles:",
  formatTime(
    new Date(nextHalfHour.getTime() + 1 * 60 * 60 * 1000),
    "America/Los_Angeles",
  ),
);

These two time zones (Europe/London, America/Los_Angeles) have a significant time difference.

If i write FunPlanat/moon instead America/Los_Angeles i still get the same result and no errors.

i wonder that i cannot provocate an error here and that the results always the same correct result for Lativa.

The formatTime function in ES6 is a custom function that takes a Date object and a time zone identifier as inputs, and returns a formatted string representation of the time in the specified time zone.

If this source correct? Or how i could fix that if not?

i was reading here about formatTime function:

• convert date time to utc format
• https://www.tutorialspoint.com/display-the-asian-and-american-date-time-with-date-object-in-javascript
• How do I format a date in JavaScript?

This is the complete source snippet that i using in https://github.com/sl5net/autocivP/commit/dd65aafff2c95d60014da8423a192cdcf68f4c70

formatTime(new Date('2023-07-08'), 'Asia/Kolkata');
// gives same result like formatTime(new Date('2023-07-08'), 'moonShip');

const tBerlinLondonSwedenDenmark = formatTime(nextHalfHour, "Europe/London");

// const tSweden = formatTime(new Date(nextHalfHour.getTime() + (1 * 60 * 60 * 1000)), 'Europe/Stockholm');
const Latvia = formatTime(
  new Date(nextHalfHour.getTime() + 1 * 60 * 60 * 1000),
  "Europe/London",
);
const RioGrandeDoSulBrasilien = formatTime(
  new Date(nextHalfHour.getTime() - 5 * 60 * 60 * 1000),
  "Europe/London",
);
const tGreece = formatTime(
  new Date(nextHalfHour.getTime() + 1 * 60 * 60 * 1000),
  "Europe/Athens",
);

const Asia_Kolkata = formatTime(
  new Date(nextHalfHour.getTime() + 3.5 * 60 * 60 * 1000),
  "Asia/Kolkata",
);
const USA_ET = formatTime(
  new Date(nextHalfHour.getTime() - 6 * 60 * 60 * 1000),
  "America/New_York",
);
const USA_Los_Angeles = formatTime(
  new Date(nextHalfHour.getTime() - 9 * 60 * 60 * 1000),
  "America/Los_Angeles",
);
const USA_Chicago = formatTime(
  new Date(nextHalfHour.getTime() - 7 * 60 * 60 * 1000),
  "America/Los_Angeles",
);

Answer 1

The FunPlanat/moon timezone is a fictional timezone used for the example. In real-world usage, you should replace it with the appropriate timezone identifier. You can find the valid timezone identifiers in the IANA Time Zone Database (https://www.iana.org/time-zones)

Write the reusable function with the parameter timezone

const formatTime = (timezone) => {
  const options = {
    timeZone: timezone,
    hour: 'numeric',
    minute: 'numeric',
    second: 'numeric',
  };

  const formatter = new Intl.DateTimeFormat(undefined, options);
  const currentTime = new Date();

  return formatter.format(currentTime);
};


const asiaKolkataTime = formatTime('Asia/Kolkata');
const americaNewYorkTime = formatTime('America/New_York');

console.log('Asia/Kolkata Time:', asiaKolkataTime);
console.log('America/New_York Time:', americaNewYorkTime);