Library to handle dates in a custom date format.

Usage no npm install needed!

<script type="module">
  import dateX from '';



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It provides the ability to compare date string with custom date format expression.


Testing dates with custom date format:

'use strict';
const dateX = require('date-x');
dateX.test("dd/MM/yyyy hh:mm:ss", "03/12/2016 11:11:32"); // true
dateX.test("dd/MM/yyyy hh:mm:ss", "03/12/2016 20:11:32"); // false

Where test is: test(format: string, dateString: string, ignoreCase?: boolean): boolean

Matching date with custom date format:

'use strict';
const dateX = require('date-x');
const m1 = dateX.match("dd/MM/yyyy hh:mm:ss", "03/12/2016 11:11:32");
// m1: [
//   '03/12/2016 11:11:32',
//   '03', '12', '2016',
//   '11', '11', '32',
//   index: 0, ...
// ]
const m2 = datex.match("dd/MM/yyyy hh:mm:ss", "03/12/2016 20:11:32");
// m2: null

Where match is: match(format: string, dateString: string, ignoreCase?: boolean): RegExpMatchArray

Support for localized matching.

Code Name
EN English (default)
HU Hungarian
NL Dutch
'use strict';
const dateX = require('date-x');
dateX.test("RRRR, EEEE", "Yesterday, Monday"); // true

dateX.test("RRRR, EEEE", "Tegnap, Hétfő"); // true

Where loadLocale is: loadLocale(local: "en" | "hu" | "nl"): void


const {
} = require("date-x/assert");

assertDateFormat("03/12/2016 11:11:32", "dd/MM/yyyy hh:mm:ss");
assertNotDateFormat("this is not a date", "yyyy-MM-dd");

Where both assertion has the following parameters:

  1. dateString: string the actual value to check
  2. format: string the date format to match
  3. options?: DateFormatAssertOptions the modifiers/options to match:
    • locale?: "hu" | "en" | "nl" the locale to use
    • ignoreCase?: boolean whether character casing should be ignored

Chai plugin

'use strict';
const chai = require('chai');

chai.expect("03/12/2016 11:11:32")"dd/MM/yyyy hh:mm:ss");

Date format string

It based on AngularJS date filter format tokens. The module will replace the tokens in the string in given order of the bellow tokens.

Token Description Example (EN)
LLLL Stand-alone month in year January-December
MMMM Month in year January-December
MMM Month in year Jan-Dec
MM Month in year, by number, padded 01-12
M Month in year, by number 1-12
yyyy 4 digit representation of year AD 1 => 0001, AD 2010 => 2010
yy 2 digit representation of year 00-99: AD 2001 => 01, AD 2010 => 10
y 1 digit representation of year AD 1 => 1, AD 199 => 199
EEEE Day in week Monday-Sunday
EEE Day in week Mon-Sun
RRRR Relative days Today, Yesterday, Tomorrow
dd Day in month, padded 01-31
d Day in month 1-31
ww Week of year, padded 00-53
w Week of year 0-53
HH Hour in day, padded 00-23
H Hour in day 0-23
hh Hour in AM/PM, padded 01-12
h Hour in AM/PM 1-12
mm Minute in hour, padded 00-59
m Minute in hour 0-59
sss Millisecond in second, padded 000-999
ss Second in minute, padded 00-59
s Second in minute 0-59
a AM/PM mark AM, PM
Z 4 digit (+sign) representation of the timezone offet -1200 - +1200

It also supports predefined localizable formats, like: short , medium , fullDate , mediumTime , etc. in all supported locales.


Using the above-listed tokens as normal characters can be done with using the ! character in fron of a character. For example to set an a in the format, use it as !a, so that it won't match for AM/PM.

If you would like to set a ! character in the format, use the !!.

In case of characters what are not listed in the format tokens, no need to use the !.