Comprehensive, yet simple, stealthy and fast. Datejs has passed all trials and is ready to strike. Datejs doesn't just parse strings, it slices them cleanly in two.



Datejs is an open source JavaScript Date library for parsing, formatting and processing.

The last 'official' release was Alpha-1 on November 19th, 2007. The project has been mostly dormant since that early release, but steps are being taken to revive the project.

A test suite is available online at

Getting Started

NOTE Please be sure to check out our blog post Getting Started with DateJS.

We recommend including one of the .js files from within the /build/ folder.

<script type="text/javascript" src="date.js"></script>

Within the /build/ folder, a date.js file has been created for each of the 150+ supported Cultures. Changing the Culture of the library is as easy as changing the date.js file.

<!-- Set the CultureInfo to de-DE (German/Deutsch) -->
<script type="text/javascript" src="date-de-DE.js"></script>

Before minification, the Datejs library is contained in five (6) separate JavaScript files. Each of the files can be included individually.

The following is a list of precedence if including the files individually. Each file requires the one above it. For example, core.js requires a CultureInfo file.

  1. CultureInfo       Contains all Globalized strings and culture specific properties.
                       Debug versions available within the /trunk/source/globalization/ folder.
  2. core.js           All core Date processing logic.
  3. parser.js         All parsing logic.
  4. sugarpak.js*      All syntactical sugar.
  5. time.js**         TimeSpan and TimePeriod classes.
  6. extras.js**       PHP/Unix date format conversion functions.

  *  The parser.js file is not required for sugarpak.js
  ** The time.js and extras.js files are optional and are not included in the compiled /build/ versions.

Example Usage

Syntax Overview                    // Returns today's date, with time set to 00:00 (start of day).    // Returns the date of the next Friday.    // Returns the date of the previous Monday.

new Date().next().march()       // Returns the date of the next March.
new Date().last().week()        // Returns the date one week ago.      // Returns true|false if the day-of-week matches.         // Abbreviated day names.    // Month names.         // Abbreviated month names.     // Is today a weekday?         // Add one day (+1).      // Subtract three months (-3).       // Add one (+1) day. Supports all date parts (year, month, day, hour, minute, second, millisecond, and weeks)   // Subtract three (-3) months.

(1).day().fromNow()             // One (1) day from now. 
(3).months().ago()              // Three (3) months ago.

var n = 6;
n.months().fromNow()            // Six (6) months from now.

Date.monday()                   // Returns Monday of the current week.
Date.mon()                      // Abbreviated version of Date.monday()

Date.march()                    // Returns March 1st of this year.
Date.mar()                      // Abbreviated version of Date.march() // Returns the first Thursday of the current month. Returns the second Thursday of the current month.

Date.march().third().thursday() // Returns the third Thursday in March of the current year.
Date.october().fourth().sunday()// Returns the fourth Sunday in October.   // Returns the fifth Sunday in the current month, or throws a RangeError exception if there are not 5 Sundays in the current month.
Date.october().final().sunday() // Returns the final Sunday in October.

Date.january().first().monday() // Returns the first Monday of the current year.
Date.december().final().friday()// Returns the last Friday of the current year."6:15pm");      // Returns todays date at 6:15pm.

var time = {hour:18, minute:15};;          // Set time with a config object.

var birthDayParty = {month: 1, day: 20, hour: 20, minute: 30};;// Set date and time with a config object.


The following list is only a small subset of hundreds of string formats which can be parsed correctly without providing a date format. All parsing is fully Globalized by including the appropriate CultureInfo file. The CultureInfo file contains all the strings used for parsing and formatting.

All CultureInfo files can be found in the /trunk/source/globalization/ folder.

The following .parse() samples use the en-US.js CultureInfo file.

Date.parse('t')                 // Returns today's date.
Date.parse('today')             // Returns today's date.
Date.parse('tomorrow')          // Returns tomorrow's date.
Date.parse('yesterday')         // Returns yesterday's date.

Date.parse('next friday')       // Returns the date of the next Friday.
Date.parse('last monday')       // Returns the date of the previous Monday.

Date.parse('July 8th, 2004')    // Thu Jul 08 2004
Date.parse('15-Jan-2004')       // Thu Jan 15 2004

Date.parse('7/1/2004')          // Thu Jul 01 2004
Date.parse('7.1.2004')          // Thu Jul 01 2004
Date.parse('07.15.04')          // Thu Jul 15 2004

Date.parse('July 23rd 2004')    // Fri Jul 23 2004
Date.parse('Sat July 3, 2004')  // Sat Jul 03 2004

Date.parse('10:30 PM EST')      // Wed Oct 31 2007 20:30:00
Date.parse('10PM')              // Wed Oct 31 2007 22:00:00

Date.parse('t + 5d')            // Adds 5 days to today.
Date.parse('today - 1 month')   // Subtracts 1 month from today.

Date.parse('+')                 // Add 1 day to today = tomorrow.
Date.parse('- 3months')         // Subtract 3 months.

Date.parse('+1year')            // Add a year to today.
Date.parse('-12 months')        // Subtract 12 months (1 year) from today.

Date.parse('July 4th')          // July 4th of this year.
Date.parse('15')                // 15th day of current month/year.

Date.parse('July 8th, 2004, 10:30 PM')      // Thu Jul 08 2004 22:30:00
Date.parse('2004-07-15T06:45:00')           // Thu Jul 15 2004 06:45:00
Date.parse('Thu, 1 July 2004 22:30:00 GMT') // Thu Jul 01 2004 16:30:00

Date.parse('1997-07-16T19:20:15')           // ISO 8601 Formats
Date.parse('1997-07-16T19:20:30+01:00')     // ISO 8601 with Timezone offset
Date.parse('1985-04-12T23:20:50Z')          // RFC 3339 Formats

Chaining{ months: 1, days: 5 }).is().fri()        // Add 1 month and 5 days, then check if that date is a Friday.
Date.parse('10-July-2004').next().friday().add(-1).month() // Take in a date, then move to the next Friday and subtract a month.

Comparison Date.parse('today'))                  // true|false
Date.parse('last Tues').equals(               // true|false

Date.equals(, Date.parse('today'))             // true|false, Date.parse('today'))            // 1 = greater, -1 = less than,'yesterday'))            // 1 = greater, -1 = less than, 0 = equal, endDate)                   // true|false

Converting to String

Note The format parameter is optional with the .toString() function. If no format is provided, the native JavaScript Date .toString() function will be called.

A detailed list of supported FormatSpecifiers is listed in the [ Wiki] documentation.

Standard Date and Time Format Specifiers

Format Description Example
s The seconds of the minute between 0-59. "0" to "59"
ss The seconds of the minute with leading zero if required. "00" to "59"
m The minute of the hour between 0-59. "0" or "59"
mm The minute of the hour with leading zero if required. "00" or "59"
h The hour of the day between 1-12. "1" to "12"
hh The hour of the day with leading zero if required. "01" to "12"
H The hour of the day between 0-23. "0" to "23"
HH The hour of the day with leading zero if required. "00" to "23"
d The day of the month between 1 and 31. "1" to "31"
dd The day of the month with leading zero if required. "01" to "31"
ddd Abbreviated day name. Date.!CultureInfo.abbreviatedDayNames. "Mon" to "Sun"
dddd The full day name. Date.!CultureInfo.dayNames. "Monday" to "Sunday"
M The month of the year between 1-12. "1" to "12"
MM The month of the year with leading zero if required. "01" to "12"
MMM Abbreviated month name. Date.!CultureInfo.abbreviatedMonthNames. "Jan" to "Dec"
MMMM The full month name. Date.!CultureInfo.monthNames. "January" to "December"
yy Displays the year as a two-digit number. "99" or "07"
yyyy Displays the full four digit year. "1999" or "2007"
t Displays the first character of the A.M./P.M. designator. Date.!CultureInfo.amDesignator or Date.!CultureInfo.pmDesignator "A" or "P"
tt Displays the A.M./P.M. designator. Date.!CultureInfo.amDesignator or Date.!CultureInfo.pmDesignator "AM" or "PM"
S The ordinal suffix ("st, "nd", "rd" or "th") of the current day. "st, "nd", "rd" or "th"

Custom Date and Time Format Specifiers

Format Description Example
d The CultureInfo shortDate Format Pattern "M/d/yyyy"
D The !CultureInfo longDate Format Pattern "dddd, MMMM dd, yyyy"
F The !CultureInfo fullDateTime Format Pattern "dddd, MMMM dd, yyyy h:mm:ss tt"
m The !CultureInfo monthDay Format Pattern "MMMM dd"
r The !CultureInfo rfc1123 Format Pattern "ddd, dd MMM yyyy HH:mm:ss GMT"
s The !CultureInfo sortableDateTime Format Pattern "yyyy-MM-ddTHH:mm:ss"
t The !CultureInfo shortTime Format Pattern "h:mm tt"
T The !CultureInfo longTime Format Pattern "h:mm:ss tt"
u The !CultureInfo universalSortableDateTime Format Pattern "yyyy-MM-dd HH:mm:ssZ"
y The !CultureInfo yearMonth Format Pattern "MMMM, yyyy"

Separator Characters

Character Name
/ forward slash
. period
- hyphen
, comma
new Date().toString()                  // "Wed Oct 31 2007 16:18:10 GMT-0700 (Pacfic Daylight Time)"
new Date().toString('M/d/yyyy')        // "10/31/2007"'d-MMM-yyyy')    // "31-Oct-2007"
new Date().toString('HH:mm')           // "16:18"'MMMM dS, yyyy') // "April 12th, 2008"       // "10/31/2007". Culture specific as per Date.CultureInfo.shortDatePattern.        // "Wednesday, October 31, 2007". Culture specific as per Date.CultureInfo.longDatePattern.

new Date().toShortTimeString()         // "4:18 PM". Culture specific as per Date.CultureInfo.shortTimePattern.
new Date().toLongTimeString()          // "4:18:34 PM". Culture specific as per Date.CultureInfo.longTimePattern.

Core{ day: 15 })          // Sets the day to the 15th of the current month and year. Other object values include year|month|day|hour|minute|second.{ year: 2007, month: 1, day: 20 }){ days: 2 })          // Adds 2 days to the Date. Other object values include year|month|day|hour|minute|second.{ years: -1, months: 6, hours: 3 })               // Adds 1 year.             // Subtracts 2 months.               // Adds 1 week.                // Adds 4 days.               // Adds 6 hours.           // Subtracts 30 minutes.            // Adds 15 seconds.      // Adds 200 milliseconds.   // Returns the first day of the current month.    // Returns the last day of the current month.

new Date().clearTime()                 // Sets the time to 00:00 (start of the day).            // Resets the time to the current time (now). The functional opposite of .clearTime()

ISO 8601

// Parse ISO 8601 string
Date.parse('\"1997-07-16T19:20:15\"')  // ISO 8601 string format with wrapping double-quotes

// Convert date to ISO 8601 string
new Date().toISOString()               // Returns ISO 8601 string of date converted to it's UTC value. "2007-10-31T16:18:00Z"

// Get UTC converted ISO week number              // Returns ISO 8601 week of year. Returns "01" to ("52" | "53") depending on the year. See also .getWeek()


Date.getMonthNumberFromName('March')   // 2 - CultureInfo specific. <static>
Date.getDayNumberFromName('sat')       // 6 - CultureInfo specific. <static>

Date.isLeapYear(2008)                  // true|false. <static>
Date.getDaysInMonth(2007, 9)           // 31 <static>                 // Returns week of year. Returns 1 to (52 | 53) depending on the year                // Sets the week of the year to the Monday of the week set.

var test = new Date();                 // Do something... like run a test...
test.getElapsed()                      // Returns millisecond difference from now.    // true|false. Is within the Daylight Saving Time.   // true|false. Is Daylight Saving Time observed.