@protontech/timezone-support/src/parse-format/format.js

Lightweight time zone support for your applications or other date libraries.

import formattingTokens from './tokens'
import { padWithZeros } from './padding'

const formatTokenFunctions = {}
const formatters = {}

function makeFormatter (format) {
  const array = format.match(formattingTokens)
  const { length } = array
  for (let i = 0; i < length; ++i) {
    const token = array[i]
    const formatter = formatTokenFunctions[token]
    if (formatter) {
      array[i] = formatter
    } else {
      array[i] = token.replace(/^\[|\]$/g, '')
    }
  }
  return function (time) {
    let output = ''
    for (let token of array) {
      output += typeof token === 'function' ? token.call(time) : token
    }
    return output
  }
}

const addFormatToken = function (token, padded, property) {
  const callback = typeof property === 'string' ? function () {
    return this[property]
  } : property
  if (token) {
    formatTokenFunctions[token] = callback
  }
  if (padded) {
    formatTokenFunctions[padded[0]] = function () {
      return padWithZeros(callback.call(this), padded[1])
    }
  }
}

addFormatToken('A', 0, function () { return this.hours < 12 ? 'AM' : 'PM' })
addFormatToken('a', 0, function () { return this.hours < 12 ? 'am' : 'pm' })
addFormatToken('S', 0, function () { return Math.floor(this.milliseconds / 100) })
addFormatToken(0, ['SS', 2], function () { return Math.floor(this.milliseconds / 10) })
addFormatToken(0, ['SSS', 3], 'milliseconds')
addFormatToken('s', ['ss', 2], 'seconds')
addFormatToken('m', ['mm', 2], 'minutes')
addFormatToken('h', ['hh', 2], function () { return (this.hours % 12) || 12 })
addFormatToken('H', ['HH', 2], 'hours')
addFormatToken('d', 0, 'dayOfWeek')
addFormatToken('D', ['DD', 2], 'day')
addFormatToken('M', ['MM', 2], 'month')
addFormatToken(0, ['YY', 2], function () { return this.year % 100 })
addFormatToken('Y', ['YYYY', 4], 'year')
addFormatToken('z', 0, function () { return this.zone.abbreviation })

function addTimeZoneFormatToken (token, separator) {
  addFormatToken(token, 0, function () {
    let offset = -this.zone.offset
    const sign = offset < 0 ? '-' : '+'
    offset = Math.abs(offset)
    return sign + padWithZeros(Math.floor(offset / 60), 2) + separator + padWithZeros(offset % 60, 2)
  })
}

addTimeZoneFormatToken('Z', ':')
addTimeZoneFormatToken('ZZ', '')

function formatZonedTime (time, format) {
  let formatter = formatters[format]
  if (!formatter) {
    formatter = formatters[format] = makeFormatter(format)
  }
  return formatter(time)
}

export { formatZonedTime }