Typescript function that takes a Date, string or moment object and converts it between timezones.

toTimezone.ts

import * as moment from "moment-timezone";

/**
 * @description 
 * @param {Date | string | moment} date Date to transform.
 * @param {string} originTZ Timezone in which the date to transform is currently. I.E. "UTC". Defaults to client PC TZ.
 * @param {string} destinationTZ Timezone to which to convert the date. I.E. "America/Los Angeles". Defaults to "UTC".
 * @return {string} Date converted to destination timezone in string.
 * 
 */
export function toTimezone(date: Date | string | moment, originTZ: string = Intl.DateTimeFormat().resolvedOptions().timeZone, destinationTZ: string = "UTC"): string {
    return moment(moment(new Date()).tz(originTz, true))
        .tz(destinationTZ)
        .format("YYYY-MM-DDTHH:mm:ss");
}

// console.log(toTimezone(new Date(), Intl.DateTimeFormat().resolvedOptions().timeZone, "UTC")) // Current PC time to UTC.