This function returns a string containing formatting data for the current date/time, based on the provided locale string.

function getDateFormatString(locale) {
    
  const options = {
    hour: "numeric",
    minute: "numeric",
    second: "numeric",
    day: "numeric",
    month: "numeric",
    year: "numeric",
  };

  const formatObj = new Intl.DateTimeFormat(locale, options).formatToParts(
    Date.now()
  );

  return formatObj
    .map((obj) => {
      switch (obj.type) {
        case "hour":
          return "HH";
        case "minute":
          return "MM";
        case "second":
          return "SS";
        case "day":
          return "DD";
        case "month":
          return "MM";
        case "year":
          return "YYYY";
        default:
          return obj.value;
      }
    })
    .join("");
}

console.log(getDateFormatString("en-US")); //Expected Output: "MM/DD/YYYY, HH:MM:SS PM"

console.log(getDateFormatString("ko-KR")); //Expected Output: "YYYY. MM. DD. 오후 HH:MM:SS"

Edit options to change the data extracted from the date object and edit/add cases to accommodate it.

Find the documentation for DateTimeFormat here.
I adapted the function from an article on newbedev.com.

At mozilla.org there are clear instructions on how to do this using the .toLocaleTimeString() function.

Examples taken directly from the website:

You can find the documentation here

// Depending on timezone, your results will vary
const event = new Date('August 19, 1975 23:15:30 GMT+00:00');

console.log(event.toLocaleTimeString('en-US'));
// expected output: 1:15:30 AM

console.log(event.toLocaleTimeString('it-IT'));
// expected output: 01:15:30

console.log(event.toLocaleTimeString('ar-EG'));
// expected output: ١٢:١٥:٣٠ص

Get time zone

- new Date().getTimezoneOffset() / 60

Obtain the time based on the time zone

const num=- new Date().getTimezoneOffset() / 60;

const newDate=new Date(new Date().getTime()+num*60*60*1000).toISOString()