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A date and time library for ClojureScript, imitating the API of the clj-time library.

Cljs-time is an attempt at replicating the functionality and API of clj-time. This is not a drop-in clojurescript replacement for clj-time, however the goal is that over time enough functionality of the clj-time API can be replicated to make this library "good enough" for other projects.

This library is currently leaning on the Google Closure library for basic date/time functionality. The date objects in this library are mutable, however any operations that alter a date object return a copy, leaving the referenced date object alone. In the future, immutable date objects will be preferred.


cljs-time artifacts are released to Clojars.

If you are using Maven, add the following repository definition to your pom.xml:


The Most Recent Release

With Leiningen:

;; Stable
[com.andrewmcveigh/cljs-time "0.5.2"]

Bugs and Enhancements

Please open issues against the cljs-time repo on Github.

Note: version 0.5. follows the API of clj-time 0.11.0.*


Most of the clj-time API has been implemented. Some of the parts that don't make sense in clojurescript, such as Java interop, and java.sql.* have been left out. Timezone functionality in javascript is minimal, and therefore so is cljs-time's.

The majority of the tests from clj-time have been ported, and are passing.

API documentation is available.


Note: Equality in* (and also with plain javascript dates) is not the same as in Joda/clj-time. Two date objects representing the same instant in time in* are not equal.

If you need to test for equality use either cljs-time.core/=, or optionally you can require the cljs-time.extend namespace which will extend the* datatypes, so that clojure.core/= works as expected.

If you want your* serializable with pr-str, require cljs-time.instant namespace.


The main namespace for date-time operations in the cljs-time library is cljs-time.core.

=> (use 'cljs-time.core)

Create a DateTime instance with date-time, specifying the year, month, day, hour, minute, second, and millisecond:

=> (date-time 1986 10 14 4 3 27 456)
#<DateTime 1986-10-14T04:03:27.456Z>

Less-significant fields can be omitted:

=> (date-time 1986 10 14)
#<DateTime 1986-10-14T00:00:00.000Z>

Get the current time with (now) and the start of the Unix epoch with (epoch).

Once you have a date-time, use accessors like hour and second to access the corresponding fields:

=> (hour (date-time 1986 10 14 22))

The date-time constructor always returns times in the UTC time zone.

If you only want a date with no time component, consider using the local-date and today functions. These return LocalDate instances that do not have time components (and thus don't suffer from timezone-related shifting).

=> (local-date 2013 3 20)
#<LocalDate 2013-03-20>

The functions after? and before? determine the relative position of two DateTime instances:

=> (after? (date-time 1986 10) (date-time 1986 9))

Often you will want to find a date some amount of time from a given date. For example, to find the time 1 month and 3 weeks from a given date-time:

=> (plus (date-time 1986 10 14) (months 1) (weeks 3))
#<DateTime 1986-12-05T00:00:00.000Z>

An Interval is used to represent the span of time between two DateTime instances. Construct one using interval, then query them using within?, overlaps?, and abuts?

=> (within? (interval (date-time 1986) (date-time 1990))
            (date-time 1987))

The in-seconds and in-minutes functions can be used to describe intervals in the corresponding temporal units:

=> (in-minutes (interval (date-time 1986 10 2) (date-time 1986 10 14)))


If you need to parse or print date-times, use cljs-time.format:

=> (use 'cljs-time.format)

Printing and parsing are controlled by formatters. You can either use one of the built in ISO8601 formatters or define your own, e.g.:

(def built-in-formatter (formatters :basic-date-time))
(def custom-formatter (formatter "yyyyMMdd"))

To see a list of available built-in formatters and an example of a date-time printed in their format:

=> (show-formatters)

Remember that mm is minutes, MM is months, ss is seconds and SSS is milliseconds.

Once you have a formatter, parsing and printing are straight-forward:

=> (parse custom-formatter "20100311")

=> (unparse custom-formatter (date-time 2010 10 3))

cljs-time.core/today-at returns a moment in time at the given hour, minute and second on the current date:

=> (today-at 12 00)
=> (today-at 12 00 05)


The namespace cljs-time.coerce contains utility functions for coercing Google Closure DateTime instances to and from various other types:

=> (use 'cljs-time.coerce)

For example, to convert a DateTime to and from a js Number:

=> (to-long (date-time 1998 4 25))

=> (from-long 893462400000)

And by the magic of protocols you can pass in an isoformat string and get the unix epoch milliseconds:

=> (to-long "2013-08-01")


Running the tests:

$ boot test-all


$ boot auto-test

Getting a REPL

$ boot repl # (or jack-in from cider/etc)
    boot.user> (node-repl)
    clojurescript node.js repl server listening on 56950
    to quit, type: :cljs/quit
    cljs.user> (+ 1 1)


The complete API documentation is also available.


Copyright © 2013-2016 Andrew Mcveigh

Distributed under the Eclipse Public License, the same as Clojure.


A clj-time inspired date library for clojurescript.