time-converting

Typescript functions to convert local time to UTC and vise versa using date-fns

import { format, parse } from 'date-fns'

const TIME_FORMAT = 'HH:mm:ss'

function utcToLocalTime(utcTime: string): string {
  const date = parse(utcTime, TIME_FORMAT, new Date())

  return format(
    new Date(
      Date.UTC(
        date.getFullYear(),
        date.getMonth(),
        date.getDate(),
        date.getHours(),
        date.getMinutes(),
        date.getSeconds(),
        date.getMilliseconds()
      )
    ),
    TIME_FORMAT
  )
}

function localTimeToUtc(localTime: string): string {
  const date = parse(localTime, TIME_FORMAT, new Date())

  return format(
    new Date(
      date.getUTCFullYear(),
      date.getUTCMonth(),
      date.getUTCDate(),
      date.getUTCHours(),
      date.getUTCMinutes(),
      date.getUTCSeconds(),
      date.getUTCMilliseconds()
    ),
    TIME_FORMAT
  )
}