dt-format/src/text/format/date/date.time.format.ts

date formatter for javascript

import { DateTimePattern } from './date.time.pattern';
import { getLocalizedMonth, getLocalizedTimeMarker, getLocalizedWeek, LocaleType } from './locale';

enum DateTimeType {
  SHORT = 'short',
  LONG = 'long',
}

enum DayTimeMarker {
  AM = 'AM',
  PM = 'PM',
}

const POSSIBLE_PATTERNS = [
  DateTimePattern.FULL_DATE,
  DateTimePattern.SHORT_DATE,
  DateTimePattern.FULL_YEAR,
  DateTimePattern.SHORT_YEAR,
  DateTimePattern.FULL_MINUTE,
  DateTimePattern.SHORT_MINUTE,
  DateTimePattern.FULL_24_HOUR,
  DateTimePattern.SHORT_24_HOUR,
  DateTimePattern.FULL_HOUR,
  DateTimePattern.SHORT_HOUR,
  DateTimePattern.FULL_SECOND,
  DateTimePattern.SHORT_SECOND,
  DateTimePattern.FULL_MILLISECOND,
  DateTimePattern.MEDIUM_MILLISECOND,
  DateTimePattern.SHORT_MILLISECOND,
  DateTimePattern.AM_PM_MARKER,
  DateTimePattern.FULL_MONTH,
  DateTimePattern.MEDIUM_MONTH,
  DateTimePattern.SHORT_MONTH,
  DateTimePattern.FULL_WEEK,
  DateTimePattern.MEDIUM_WEEK,
  DateTimePattern.SHORT_WEEK,
];

const getDayTimeMarker =
  (locale: LocaleType, type: DayTimeMarker) => getLocalizedTimeMarker(locale)[type];
const getWeek =
  (week: number, key: string, locale: LocaleType) => getLocalizedWeek(locale)[`${week}`][key];
const getMonth =
  (month: number, key: string, locale: LocaleType) => getLocalizedMonth(locale)[`${month}`][key];
const suffixWithZero =
  (value: number, comparator: number = 9) => value <= comparator ? `0${value}` : `${value}`;
const calculateIn12HourFormat = (value: number) => value > 12 ? value - 12 : value;

const getDateValue = (date: Date, pattern: DateTimePattern, locale: LocaleType) => {
  switch (pattern) {
    case DateTimePattern.SHORT_DATE:
      return `${date.getDate()}`;
    case DateTimePattern.FULL_DATE:
      return suffixWithZero(date.getDate());
    case DateTimePattern.SHORT_YEAR:
      return `${date.getFullYear()}`.substring(2);
    case DateTimePattern.FULL_YEAR:
      return `${date.getFullYear()}`;
    case DateTimePattern.SHORT_MONTH:
      return suffixWithZero(date.getMonth() + 1);
    case DateTimePattern.MEDIUM_MONTH:
      return getMonth(date.getMonth(), DateTimeType.SHORT, locale);
    case DateTimePattern.FULL_MONTH:
      return getMonth(date.getMonth(), DateTimeType.LONG, locale);
    case DateTimePattern.SHORT_WEEK:
      return suffixWithZero(date.getDay());
    case DateTimePattern.MEDIUM_WEEK:
      return getWeek(date.getDay(), DateTimeType.SHORT, locale);
    case DateTimePattern.FULL_WEEK:
      return getWeek(date.getDay(), DateTimeType.LONG, locale);
    case DateTimePattern.FULL_MINUTE:
      return suffixWithZero(date.getMinutes());
    case DateTimePattern.SHORT_MINUTE:
      return date.getMinutes();
    case DateTimePattern.SHORT_24_HOUR:
      return date.getHours();
    case DateTimePattern.FULL_24_HOUR:
      return suffixWithZero(date.getHours());
    case DateTimePattern.SHORT_HOUR:
      return calculateIn12HourFormat(date.getHours());
    case DateTimePattern.FULL_HOUR:
      return suffixWithZero(calculateIn12HourFormat(date.getHours()));
    case DateTimePattern.SHORT_SECOND:
      return date.getSeconds();
    case DateTimePattern.FULL_SECOND:
      return suffixWithZero(date.getSeconds());
    case DateTimePattern.SHORT_MILLISECOND:
      return date.getMilliseconds();
    case DateTimePattern.MEDIUM_MILLISECOND:
      return suffixWithZero(date.getMilliseconds());
    case DateTimePattern.FULL_MILLISECOND:
      return suffixWithZero(date.getMilliseconds(), 99);
    case DateTimePattern.AM_PM_MARKER:
      return date.getHours() >= 12
        ? getDayTimeMarker(locale, DayTimeMarker.PM)
        : getDayTimeMarker(locale, DayTimeMarker.AM);
    default:
      return '';
  }
};

export class DateTimeFormat {
  public static format(date: Date, pattern: string, locale: LocaleType = LocaleType.en_GB): string {
    let value = pattern;
    POSSIBLE_PATTERNS.forEach((possiblePattern: string) => {
      while (value.indexOf(possiblePattern) !== -1) {
        const dateValue = getDateValue(date, possiblePattern as DateTimePattern, locale);
        value = value.replace(possiblePattern, dateValue);
      }
    });

    return value;
  }
}