Fixed the toDate bug occurring when parsing ISO-8601 style dates (but not valid ISO format) with a trailing Z (e.g 2012-01Z), it returned Invalid Date for FireFox/IE11 #510
Fixed differenceIn... functions returning negative zero in some cases: #692
isDate now works properly with dates passed across iframes #754.
Fixed a few bugs that appeared in timezones with offsets that include seconds (e.g. GMT+00:57:44). See PR #789.
Fixed DST issue. See #972 and #992 for more details.
Fixed DST issue in eachDayOfInterval that caused time in the days after DST change to have the shift as well.
Fixed bug in Galician locale caused by incorrect usage of getHours instead of getUTCHours.

Changed

BREAKING: now functions don't accept string arguments, but only numbers or dates. When a string is passed, it will result in an unexpected result (Invalid Date, NaN, etc).

From now on a string should be parsed using parseISO (ISO 8601) or parse.

In v1 we've used new Date() to parse strings, but it resulted in many hard-to-track bugs caused by inconsistencies in different browsers. To address that we've implemented our ISO 8601 parser but that made library to significantly grow in size. To prevent inevitable bugs and keep the library tiny, we made this trade-off.

See this post for more details.
```
// Before v2.0.0
addDays("2016-01-01", 1);

// v2.0.0 onward
addDays(parseISO("2016-01-01"), 1);
```
BREAKING: new format string API for format function which is based on Unicode Technical Standard #35. See this post for more details.

| Unit | ------------------------------- | Era | | GGGG | | Calendar year | y | | yo | | yy | | yyy | | yyyy | | Local week-numbering year | Y | | Yo | | YY | | YYY | | YYYY | | ISO week-numbering year | R | | RR | | RRR | | RRRR | | Extended year | u | | uu | | uuu | | uuuu | | Quarter (formatting) | Q | | Qo | | QQ | | QQQ | | QQQQ | | Quarter (stand-alone) | q | | qo | | qq | | qqq | | qqqq | | Month (formatting) | M | | Mo | | MM | | MMM | | MMMM | | Month (stand-alone) | L | | Lo | | LL | | LLL | | LLLL | | Local week of year | w | | wo | | ww | ISO week of year | I | | Io | | II | Day of month | d | | do | | dd | Day of year | D | | Do | | DD | | DDD | | DDDD | Day of week (formatting) | | EEEE | | | ISO day of week (formatting) | i | | io | | ii | | iii | | iiii | | | Local day of week (formatting) | e | | eo | | ee | | eee | | eeee | | | Local day of week (stand-alone) | c | | co | | cc | | ccc | | cccc | | | AM, PM | | aaaa | | AM, PM, noon, midnight | | bbbb | | Flexible day period | | BBBB | | Hour [1-12] | h | | ho | | hh | Hour [0-23] | H | | Ho | | HH | Hour [0-11] | K | | Ko | | KK | Hour [1-24] | k | | ko | | kk | Minute | m | | mo | | mm | Second | s | | so | | ss | Fraction of second | S | | SS | | SSS | | SSSS | Timezone (ISO-8601 w/ Z) | X | | XX | | XXX | | XXXX | | Timezone (ISO-8601 w/o Z) | x | | xx | | xxx | | xxxx | | Timezone (GMT) | | OOOO | Timezone (specific non-locat.) | z...zzz | | zzzz | Seconds timestamp | t | | tt | Milliseconds timestamp | T | | TT | Long localized date | P | | PP | | PPP | | PPPP | Long localized time | p | | pp | | ppp | | pppp | Combination of date and time | Pp | | PPpp | | | v2 Pattern | v1 Pattern | Result examples | | ---------- | ---------- | --------------------------------- | | G..GGG | | AD, BC | | | Anno Domini, Before Christ | | GGGGG | | A, B | | | 44, 1, 1900, 2017 | | | 44th, 1st, 0th, 17th | | YY | 44, 01, 00, 17 | | | 044, 001, 1900, 2017 | | YYYY | 0044, 0001, 1900, 2017 | | yyyyy | | ... | | | 44, 1, 1900, 2017 | | | 44th, 1st, 1900th, 2017th | | | 44, 01, 00, 17 | | | 044, 001, 1900, 2017 | | | 0044, 0001, 1900, 2017 | | YYYYY | | ... | | | -43, 0, 1, 1900, 2017 | | GG | -43, 00, 01, 1900, 2017 | | | -043, 000, 001, 1900, 2017 | | GGGG | -0043, 0000, 0001, 1900, 2017 | | RRRRR | | ... | | | -43, 0, 1, 1900, 2017 | | | -43, 01, 1900, 2017 | | | -043, 001, 1900, 2017 | | | -0043, 0001, 1900, 2017 | | uuuuu | | ... | | | 1, 2, 3, 4 | | | 1st, 2nd, 3rd, 4th | | | 01, 02, 03, 04 | | | Q1, Q2, Q3, Q4 | | | 1st quarter, 2nd quarter, ... | | QQQQQ | | 1, 2, 3, 4 | | Q | 1, 2, 3, 4 | | Qo | 1st, 2nd, 3rd, 4th | | | 01, 02, 03, 04 | | | Q1, Q2, Q3, Q4 | | | 1st quarter, 2nd quarter, ... | | qqqqq | | 1, 2, 3, 4 | | | 1, 2, ..., 12 | | | 1st, 2nd, ..., 12th | | | 01, 02, ..., 12 | | | Jan, Feb, ..., Dec | | | January, February, ..., December | | MMMMM | | J, F, ..., D | | M | 1, 2, ..., 12 | | | 1st, 2nd, ..., 12th | | MM | 01, 02, ..., 12 | | MMM | Jan, Feb, ..., Dec | | MMMM | January, February, ..., December | | LLLLL | | J, F, ..., D | | | 1, 2, ..., 53 | | | 1st, 2nd, ..., 53th | | | 01, 02, ..., 53 | | W | 1, 2, ..., 53 | | Wo | 1st, 2nd, ..., 53th | | WW | 01, 02, ..., 53 | | D | 1, 2, ..., 31 | | Do | 1st, 2nd, ..., 31st | | DD | 01, 02, ..., 31 | | DDD | 1, 2, ..., 365, 366 | | DDDo | 1st, 2nd, ..., 365th, 366th | | | 01, 02, ..., 365, 366 | | DDDD | 001, 002, ..., 365, 366 | | | ... | | E..EEE | | Mon, Tue, Wed, ..., Su | | | Monday, Tuesday, ..., Sunday | | EEEEE | | M, T, W, T, F, S, S | | EEEEEE | | Mo, Tu, We, Th, Fr, Sa, Su | | E | 1, 2, 3, ..., 7 | | do | 1st, 2nd, ..., 7th | | | 01, 02, ..., 07 | | ddd | Mon, Tue, Wed, ..., Su | | dddd | Monday, Tuesday, ..., Sunday | | iiiii | | M, T, W, T, F, S, S | | iiiiii | dd | Mo, Tu, We, Th, Fr, Sa, Su | | | 2, 3, 4, ..., 1 | | | 2nd, 3rd, ..., 1st | | | 02, 03, ..., 01 | | | Mon, Tue, Wed, ..., Su | | | Monday, Tuesday, ..., Sunday | | eeeee | | M, T, W, T, F, S, S | | eeeeee | | Mo, Tu, We, Th, Fr, Sa, Su | | | 2, 3, 4, ..., 1 | | | 2nd, 3rd, ..., 1st | | | 02, 03, ..., 01 | | | Mon, Tue, Wed, ..., Su | | | Monday, Tuesday, ..., Sunday | | ccccc | | M, T, W, T, F, S, S | | cccccc | | Mo, Tu, We, Th, Fr, Sa, Su | | a..aaa | A | AM, PM | | aa | a.m., p.m. | | aaaaa | | a, p | | b..bbb | | AM, PM, noon, midnight | | | a.m., p.m., noon, midnight | | bbbbb | | a, p, n, mi | | B..BBB | | at night, in the morning, ... | | | at night, in the morning, ... | | BBBBB | | at night, in the morning, ... | | | 1, 2, ..., 11, 12 | | | 1st, 2nd, ..., 11th, 12th | | | 01, 02, ..., 11, 12 | | | 0, 1, 2, ..., 23 | | | 0th, 1st, 2nd, ..., 23rd | | | 00, 01, 02, ..., 23 | | | 1, 2, ..., 11, 0 | | | 1st, 2nd, ..., 11th, 0th | | | 1, 2, ..., 11, 0 | | | 24, 1, 2, ..., 23 | | | 24th, 1st, 2nd, ..., 23rd | | | 24, 01, 02, ..., 23 | | | 0, 1, ..., 59 | | | 0th, 1st, ..., 59th | | | 00, 01, ..., 59 | | | 0, 1, ..., 59 | | | 0th, 1st, ..., 59th | | | 00, 01, ..., 59 | | | 0, 1, ..., 9 | | | 00, 01, ..., 99 | | | 000, 0001, ..., 999 | | | ... | | | -08, +0530, Z | | | -0800, +0530, Z | | | -08:00, +05:30, Z | | | -0800, +0530, Z, +123456 | | XXXXX | | -08:00, +05:30, Z, +12:34:56 | | | -08, +0530, +00 | | ZZ | -0800, +0530, +0000 | | Z | -08:00, +05:30, +00:00 | | | -0800, +0530, +0000, +123456 | | xxxxx | | -08:00, +05:30, +00:00, +12:34:56 | | O...OOO | | GMT-8, GMT+5:30, GMT+0 | | | GMT-08:00, GMT+05:30, GMT+00:00 | | | GMT-8, GMT+5:30, GMT+0 | | | GMT-08:00, GMT+05:30, GMT+00:00 | | X | 512969520 | | | ... | | x | 512969520900 | | | ... | | | 5/29/53 | | | May 29, 1453 | | | May 29th, 1453 | | | Sunday, May 29th, 1453 | | | 12:00 AM | | | 12:00:00 AM | | | 12:00:00 AM GMT+2 | | | 12:00:00 AM GMT+02:00 | | | 5/29/53, 12:00 AM | | | May 29, 1453, 12:00 AM | | PPPppp | | May 29th, 1453 at ... | | PPPPpppp | | Sunday, May 29th, 1453 at ... |

Characters are now escaped using single quote symbols (') instead of square brackets. format now throws RangeError if it encounters an unescaped latin character that isn't a valid formatting token.

To use YY and YYYY tokens that represent week-numbering years, you should set useAdditionalWeekYearTokens option:
```
format(Date.now(), "YY", { useAdditionalWeekYearTokens: true });
//=> '86'
```
To use D and DD tokens which represent days of the year, set useAdditionalDayOfYearTokens option:
```
format(Date.now(), "D", { useAdditionalDayOfYearTokens: true });
//=> '364'
```

BREAKING: function submodules now use camelCase naming schema:

// Before v2.0.0
import differenceInCalendarISOYears from "date-fns/difference_in_calendar_iso_years";

// v2.0.0 onward
import differenceInCalendarISOYears from "date-fns/differenceInCalendarISOYears";

BREAKING: min and max functions now accept an array of dates rather than spread arguments.

// Before v2.0.0
var date1 = new Date(1989, 6 /* Jul */, 10);
var date2 = new Date(1987, 1 /* Feb */, 11);

var minDate = min(date1, date2);
var maxDate = max(date1, date2);

// v2.0.0 onward:
var dates = [
  new Date(1989, 6 /* Jul */, 10),
  new Date(1987, 1 /* Feb */, 11),
];

var minDate = min(dates);
var maxDate = max(dates);

BREAKING: make the second argument of format required for the sake of explicitness.

// Before v2.0.0
format(new Date(2016, 0, 1));

// v2.0.0 onward
format(new Date(2016, 0, 1), "yyyy-MM-dd'T'HH:mm:ss.SSSxxx");

BREAKING renamed ISO week-numbering year helpers:
- addISOYears → addISOWeekYears
- differenceInCalendarISOYears → differenceInCalendarISOWeekYears
- differenceInISOYears → differenceInISOWeekYears
- endOfISOYear → endOfISOWeekYear
- getISOYear → getISOWeekYear
- isSameISOYear → isSameISOWeekYear
- lastDayOfISOYear → lastDayOfISOWeekYear
- setISOYear → setISOWeekYear
- subISOYears → subISOWeekYears
i.e. "ISO year" renamed to "ISO week year", which is short for ISO week-numbering year. It makes them consistent with locale-dependent week-numbering year helpers, e.g., startOfWeekYear.

BREAKING: functions renamed:

areRangesOverlapping → areIntervalsOverlapping
eachDay → eachDayOfInterval
getOverlappingDaysInRanges → getOverlappingDaysInIntervals
isWithinRange → isWithinInterval

This change was made to mirror the use of the word "interval" in standard ISO 8601:2004 terminology:

2.1.3
time interval
part of the time axis limited by two instants

Also these functions now accept an object with start and end properties instead of two arguments as an interval. All these functions throw RangeError if the start of the interval is after its end or if any date in the interval is Invalid Date.

// Before v2.0.0

areRangesOverlapping(
  new Date(2014, 0, 10),
  new Date(2014, 0, 20),
  new Date(2014, 0, 17),
  new Date(2014, 0, 21),
);

eachDay(new Date(2014, 0, 10), new Date(2014, 0, 20));

getOverlappingDaysInRanges(
  new Date(2014, 0, 10),
  new Date(2014, 0, 20),
  new Date(2014, 0, 17),
  new Date(2014, 0, 21),
);

isWithinRange(
  new Date(2014, 0, 3),
  new Date(2014, 0, 1),
  new Date(2014, 0, 7),
);

// v2.0.0 onward

areIntervalsOverlapping(
  { start: new Date(2014, 0, 10), end: new Date(2014, 0, 20) },
  { start: new Date(2014, 0, 17), end: new Date(2014, 0, 21) },
);

eachDayOfInterval({
  start: new Date(2014, 0, 10),
  end: new Date(2014, 0, 20),
});

getOverlappingDaysInIntervals(
  { start: new Date(2014, 0, 10), end: new Date(2014, 0, 20) },
  { start: new Date(2014, 0, 17), end: new Date(2014, 0, 21) },
);

isWithinInterval(new Date(2014, 0, 3), {
  start: new Date(2014, 0, 1),
  end: new Date(2014, 0, 7),
});

BREAKING: functions renamed:
- distanceInWords → formatDistance
- distanceInWordsStrict → formatDistanceStrict
- distanceInWordsToNow → formatDistanceToNow
to make them consistent with format and formatRelative.

BREAKING: The order of arguments of distanceInWords and distanceInWordsStrict is swapped to make them consistent with differenceIn... functions.

// Before v2.0.0

distanceInWords(
  new Date(1986, 3, 4, 10, 32, 0),
  new Date(1986, 3, 4, 11, 32, 0),
  { addSuffix: true },
); //=> 'in about 1 hour'

// v2.0.0 onward

formatDistance(
  new Date(1986, 3, 4, 11, 32, 0),
  new Date(1986, 3, 4, 10, 32, 0),
  { addSuffix: true },
); //=> 'in about 1 hour'

BREAKING: partialMethod option in formatDistanceStrict is renamed to roundingMethod.

// Before v2.0.0

distanceInWordsStrict(
  new Date(1986, 3, 4, 10, 32, 0),
  new Date(1986, 3, 4, 10, 33, 1),
  { partialMethod: "ceil" },
); //=> '2 minutes'

// v2.0.0 onward

formatDistanceStrict(
  new Date(1986, 3, 4, 10, 33, 1),
  new Date(1986, 3, 4, 10, 32, 0),
  { roundingMethod: "ceil" },
); //=> '2 minutes'

BREAKING: in formatDistanceStrict, if roundingMethod is not specified, it now defaults to round instead of floor.

BREAKING: unit option in formatDistanceStrict now accepts one of the strings: 'second', 'minute', 'hour', 'day', 'month' or 'year' instead of 's', 'm', 'h', 'd', 'M' or 'Y'

// Before v2.0.0

distanceInWordsStrict(
  new Date(1986, 3, 4, 10, 32, 0),
  new Date(1986, 3, 4, 10, 33, 1),
  { unit: "m" },
);

// v2.0.0 onward

formatDistanceStrict(
  new Date(1986, 3, 4, 10, 33, 1),
  new Date(1986, 3, 4, 10, 32, 0),
  { unit: "minute" },
);

BREAKING: parse that previously used to convert strings and numbers to dates now parses only strings in an arbitrary format specified as an argument. Use toDate to coerce numbers and parseISO to parse ISO 8601 strings.

// Before v2.0.0
parse("2016-01-01");
parse(1547005581366);
parse(new Date()); // Clone the date

// v2.0.0 onward
parse("2016-01-01", "yyyy-MM-dd", new Date());
parseISO("2016-01-01");
toDate(1547005581366);
toDate(new Date()); // Clone the date

BREAKING: toDate (previously parse) now doesn't accept string arguments but only numbers and dates. toDate called with an invalid argument will return Invalid Date.

BREAKING: new locale format. See docs/Locale. Locales renamed:

en → en-US
zh_cn → zh-CN
zh_tw → zh-TW

// Before v2.0.0
import locale from "date-fns/locale/zh_cn";

// v2.0.0 onward
import locale from "date-fns/locale/zh-CN";

BREAKING: now closestTo and closestIndexTo don't throw an exception when the second argument is not an array, and return Invalid Date instead.
BREAKING: now isValid doesn't throw an exception if the first argument is not an instance of Date. Instead, argument is converted beforehand using toDate.

Examples:

| isValid argument | Before v2.0.0 | v2.0.0 onward | | ------------------------- | ------------- | ------------- | | new Date() | true | true | | new Date('2016-01-01') | true | true | | new Date('') | false | false | | new Date(1488370835081) | true | true | | new Date(NaN) | false | false | | '2016-01-01' | TypeError | false | | '' | TypeError | false | | 1488370835081 | TypeError | true | | NaN | TypeError | false |

We introduce this change to make date-fns consistent with ECMAScript behavior that try to coerce arguments to the expected type (which is also the case with other date-fns functions).
BREAKING: functions now throw RangeError if optional values passed to options are not undefined or have expected values. This change is introduced for consistency with ECMAScript standard library which does the same.
BREAKING: format, formatDistance (previously distanceInWords) and formatDistanceStrict (previously distanceInWordsStrict) now throw RangeError if one of the passed arguments is invalid. It reflects behavior of toISOString and Intl API. See #1032.
BREAKING: all functions now implicitly convert arguments by following rules:

| | date | number | string | boolean | | --------- | ------------ | ------ | ----------- | ------- | | 0 | new Date(0) | 0 | '0' | false | | '0' | Invalid Date | 0 | '0' | false | | 1 | new Date(1) | 1 | '1' | true | | '1' | Invalid Date | 1 | '1' | true | | true | Invalid Date | NaN | 'true' | true | | false | Invalid Date | NaN | 'false' | false | | null | Invalid Date | NaN | 'null' | false | | undefined | Invalid Date | NaN | 'undefined' | false | | NaN | Invalid Date | NaN | 'NaN' | false |

Notes:
- as before, arguments expected to be Date are converted to Date using date-fns' toDate function;
- arguments expected to be numbers are converted to integer numbers using our custom toInteger implementation (see #765);
- arguments expected to be strings are converted to strings using JavaScript's String function;
- arguments expected to be booleans are converted to boolean using JavaScript's Boolean function.
null and undefined passed to optional arguments (i.e. properties of options argument) are ignored as if no argument was passed.

If any resulting argument is invalid (i.e. NaN for numbers and Invalid Date for dates), an invalid value will be returned:
- false for functions that return booleans (expect isValid);
- Invalid Date for functions that return dates;
- and NaN for functions that return numbers.
See tests and PRs #460 and #765 for exact behavior.
BREAKING: all functions now check if the passed number of arguments is less than the number of required arguments and will throw TypeError exception if so.
BREAKING: all functions that accept numbers as arguments, now coerce values using Number() and also round off decimals. Positive decimals are rounded using Math.floor, decimals less than zero are rounded using Math.ceil.
BREAKING: The Bower & UMD/CDN package versions are no longer supported.
BREAKING: null now is not a valid date. isValid(null) returns false; toDate(null) returns an invalid date. Since toDate is used internally by all the functions, operations over null will also return an invalid date. See #537 for the reasoning.
toDate (previously parse) and isValid functions now accept any type as the first argument.
Exclude docs.json from the npm package. Kudos to @hawkrives.

Added

FP functions like those in lodash, that support currying, and, as a consequence, functional-style function composing.

Functions with options (format, parse, etc.) have two FP counterparts: one that has the options object as its first argument and one that hasn't. The name of the former has WithOptions added to the end of its name.

In FP functions, the order of arguments is reversed.

See FP Guide for more information.

import addYears from "date-fns/fp/addYears";
import formatWithOptions from "date-fns/fp/formatWithOptions";
import eo from "date-fns/locale/eo";

// If FP function has not received enough arguments, it returns another function
const addFiveYears = addYears(5);

// Several arguments can be curried at once
const dateToString = formatWithOptions({ locale: eo }, "d MMMM yyyy");

const dates = [
  new Date(2017, 0 /* Jan */, 1),
  new Date(2017, 1 /* Feb */, 11),
  new Date(2017, 6 /* Jul */, 2),
];

const formattedDates = dates.map((date) => dateToString(addFiveYears(date)));
//=> ['1 januaro 2022', '11 februaro 2022', '2 julio 2022']

Added support for ECMAScript Modules.

It allows usage with bundlers that support tree-shaking, like rollup.js and webpack:

// Without tree-shaking:
import format from "date-fns/format";
import parse from "date-fns/parse";

// With tree-shaking:
import { format, parse } from "date-fns";

Also, ESM functions provide default export, they can be used with TypeScript to import functions in more idiomatic way:

// Before
import * as format from "date-fns/format";

// Now
import format from "date-fns/format";

formatRelative function. See formatRelative
Flow typings for index.js, fp/index.js, locale/index.js, and their ESM equivalents. See PR #558
New locale-dependent week-numbering year helpers:
- getWeek
- getWeekYear
- setWeek
- setWeekYear
- startOfWeekYear
Added eachWeekOfInterval, the weekly equivalent of eachDayOfInterval
Added getUnixTime function. Kudos to @Kingwl.
New decade helpers. Thanks to @y-nk!
- getDecade
- startOfDecade
- endOfDecade
- lastDayOfDecade
New roundToNearestMinutes function. Kudos to @xkizer.
Added new function fromUnixTime. Thanks to @xkizer.
New interval, month, and year helpers to fetch a list of all Saturdays and Sundays (weekends) for a given date interval. eachWeekendOfInterval is the handler function while the other two are wrapper functions. Kudos to @laekettavong!
- eachWeekendOfInterval
- eachWeekendOfMonth
- eachWeekendOfYear
Build-efficient lightFormat that only supports the popular subset of tokens. See #1050.
parseISO function that parses ISO 8601 strings. See #1023.
Add constants that can be imported directly from date-fns or the submodule date-fns/constants:
- maxTime
- minTime
New locales:
- Norwegian Nynorsk locale (nn) by @draperunner.
- Ukrainian locale (ua) by @korzhyk.
- Vietnamese locale (vi) by @trongthanh.
- Persian locale (fa-IR) by @mort3za.
- Latvian locale (lv) by @prudolfs.
- Bengali locale (bb) by @nutboltu and @touhidrahman.
- Hungarian (hu) and Lithuanian (lt) locales by @izifortune and pardoeryanair.
- Canadian English locale (en-CA) by @markowsiak.
- Great Britain English locale (en-GB) by @glintik.
- Uighur locale (ug) by @abduwaly.
Added new function differenceInBusinessDays which calculates the difference in business days. Kudos to @ThorrStevens!
Added new function addBusinessDays, similar to addDays but ignoring weekends. Thanks to @ThorrStevens!