Date Utilities

The Date utilities provide functions for formatting and manipulating dates in JavaScript.

Functions

formatDate

function formatDate(date, format = 'LLL', options = {})

Formats a date according to the specified format string and options.

International Support This function uses Intl.DateTimeFormat internally, please refer to the associated docs for details on timezone and formatting usage. Formatter instances are cached internally for performance, so repeated calls with the same locale and timezone avoid re-creating Intl.DateTimeFormat objects.

Timezone Lookup You can use IANA.org’s guide to look up supported timezones.

Local Timezone Usage When the ‘local’ keyword is used for the timezone option, the function will use the local timezone of the environment where the code is running. This is particularly useful for displaying dates in the user’s local time without needing to detect the timezone programmatically.

Timezone Shorthand

formatDate accepts shorthand timezone aliases alongside full IANA names. The aliases live in formatDate.config.timezones, a shorthand-to-IANA map you can edit once at app boot — abbreviations are ambiguous by nature (IST is Kolkata, Jerusalem, or Dublin depending on who you ask), so the picks are yours to remap. Full IANA names always pass through untouched.

formatDate.config.timezones = {
  // North America
  ET: 'America/New_York',
  CT: 'America/Chicago',
  MT: 'America/Denver',
  PT: 'America/Los_Angeles',
  AKT: 'America/Anchorage',
  HT: 'Pacific/Honolulu',
  AT: 'America/Halifax',

  // South America
  BRT: 'America/Sao_Paulo',

  // Europe
  UK: 'Europe/London',
  WET: 'Europe/London',
  CET: 'Europe/Paris',
  ECT: 'Europe/Paris',
  EET: 'Europe/Helsinki',
  IRST: 'Europe/Dublin',

  // Australia/Oceania
  AET: 'Australia/Sydney',
  ACT: 'Australia/Adelaide',
  AWT: 'Australia/Perth',
  NZT: 'Pacific/Auckland',

  // Asia
  IST: 'Asia/Kolkata',
  INST: 'Asia/Kolkata',
  JST: 'Asia/Tokyo',
  SGT: 'Asia/Singapore',
};

// remap an ambiguous alias for your app, once
formatDate.config.timezones.IST = 'Asia/Jerusalem';

Parameters

Name	Type	Default	Description
date	Date		The date to format
format	string	‘LLL’	The format string (e.g., ‘YYYY-MM-DD’, ‘LT’, ‘LL’)
options	object		Additional formatting options

Options

Name	Type	Default	Description
locale	string	‘default’	The locale to use for formatting
hour12	boolean	true	Whether to use 12-hour time. When `false`, the `hh` and `h` tokens output 24-hour values and the `a` token outputs an empty string.
timezone	string	‘UTC’	The timezone to use. Use `'local'` for the browser’s local timezone.

Returns

A formatted date string, or 'Invalid Date' if the input is not a valid date.

Format Tokens

Token	Output	Example
`YYYY`	4-digit year	`2023`
`YY`	2-digit year	`23`
`MMMM`	Full month name	`January`
`MMM`	3-letter month	`Jan`
`MM`	Zero-padded month	`01`
`M`	Month number	`1`
`DD`	Zero-padded day	`05`
`D`	Day number	`5`
`Do`	Day with ordinal suffix	`5th`
`dddd`	Full weekday name	`Thursday`
`ddd`	3-letter weekday	`Thu`
`HH`	24-hour padded	`14`
`hh`	12-hour padded (or 24-hour when `hour12: false`)	`02`
`h`	12-hour (or 24-hour when `hour12: false`)	`2`
`mm`	Zero-padded minutes	`05`
`ss`	Zero-padded seconds	`09`
`a`	am/pm (empty when `hour12: false`)	`pm`

Text inside square brackets is treated as a literal and passed through without replacement: [Today is] dddd outputs Today is Thursday.

Preset Formats

Preset	Pattern	Example
`LT`	`h:mm a`	`3:34 pm`
`LTS`	`h:mm:ss a`	`3:34:56 pm`
`L`	`MM/DD/YYYY`	`05/18/2023`
`l`	`M/D/YYYY`	`5/18/2023`
`LL`	`MMMM D, YYYY`	`May 18, 2023`
`ll`	`MMM D, YYYY`	`May 18, 2023`
`LLL`	`MMMM D, YYYY h:mm a`	`May 18, 2023 3:34 pm`
`lll`	`MMM D, YYYY h:mm a`	`May 18, 2023 3:34 pm`
`LLLL`	`dddd, MMMM D, YYYY h:mm a`	`Thursday, May 18, 2023 3:34 pm`
`llll`	`ddd, MMM D, YYYY h:mm a`	`Thu, May 18, 2023 3:34 pm`

Example

import { formatDate } from '@semantic-ui/utils';

const date = new Date('2023-05-15T14:30:00Z');

console.log(formatDate(date)); // "May 15, 2023 2:30 pm"
console.log(formatDate(date, 'YYYY-MM-DD')); // "2023-05-15"
console.log(formatDate(date, 'LT', { timezone: 'America/New_York' })); // "10:30 am"
console.log(formatDate(date, 'LT', { timezone: 'ET' })); // "10:30 am" (shorthand)
console.log(formatDate(date, 'LT', { timezone: 'local' })); // Formats using the local timezone

// 24-hour format — hh and h give 24h values, a gives empty string
console.log(formatDate(date, 'HH:mm', { hour12: false })); // "14:30"
console.log(formatDate(date, 'hh:mm a', { hour12: false })); // "14:30 "

// Escaped literal text
console.log(formatDate(date, '[Today is] dddd, MMMM Do, YYYY')); // "Today is Monday, May 15th, 2023"

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