Reporting Issues

To report an issue please file a question on under the ClojureScript category and tag it with problem. CLJS developers can assess and determine whether it is an issue. If needed, they can file a ticket in the ClojureScript issue tracker.

It’s important that before submitting any issue that you have a thorough understanding of the Quick Start first. Even if you are an experienced ClojureScript developer this is required reading.

It’s helpful, but not essential, to first check the existing bug reports, the mailing list, or the Freenode #clojurescript IRC channel or Slack channels and ensure that the issue hasn’t been reported before.

Also, it can be helpful to ensure that you are running the latest released version of ClojureScript. Also, checking against ClojureScript master is prudent—frequently when bugs are found, fixes are quickly committed (see instructions below).

It is essential, however, to report the bug using ClojureScript only. Downstream tooling often interacts with the ClojureScript compiler in non-trivial ways, and the best way to isolate the issue to ClojureScript is to remove them from the report altogether.

Please report issues by building the uberjar from master and using this to verify the issue. Using cljs.main with this uberjar to create a minimal repro is ideal. Alternatively, using clj and deps.edn is acceptable. Do not use any other 3rd party tooling (Maven, Leiningen, Boot). When creating issues please add all relevant instructions and code to reproduce to the ticket directly or via additional comments. Please do not attach projects, links to projects, links to gists / pastebins, or zips.

Bootstrap issues may require special consideration. Please see Reporting Bootstrap Issues for more details.

Building the uberjar from master

Make a checkout of the ClojureScript repository. From the root of the project run the following:


This will create target/cljs.jar.

Installing from master

When verifying issues it may be useful to first check that the issue has not already been resolved in master. Do not report issues using this method, it’s only for convenience when verifying master yourself. Make a checkout of the ClojureScript repository. From the root of the project run the following:


This will install ClojureScript into your local Maven. Make note of the version when it scrolls by. Use this as appropriate for your tooling.

Pinpointing Regressions with git bisect

If you’ve discovered a regression, it is helpful to identify information regarding the first bad commit when reporting issues. This is easy to do by first depending on a checkout of ClojureScript as a local root dependency and then using git bisect.

For this example, let’s say you’ve discovered a regression that is reproducible directly in the REPL (variations on the below can be employed if not).

First checkout ClojureScript master and cd to the top of the checkout tree.

Assuming you can reproduce the issue on master, but that things worked with ClojureScript 1.10.748, issue these commands at the top of the checkout tree:

git bisect start
git bisect bad HEAD
git bisect good r1.10.748

Then (in another directory) start up a REPL against the current state of the checkout tree by issuing:

clj -Srepro -Sdeps '{:deps {org.clojure/clojurescript {:local/root "/<path-to-checkout>/clojurescript"}}}' -m cljs.main -r

Test to see if you can reproduce the issue in the REPL and then exit the REPL.

If you couldn’t reproduce the problem, issue this in the ClojureScript checkout tree:

git bisect good

Or, if you were able to reproduce the problem:

git bisect bad

If the bisect is complete, git will indicate that a certain commit hash "is the first bad commit." Copy all of this text for JIRA.

Otherwise restart the REPL and repeat the above steps until done.

When finished, you can issue this to restore your ClojureScript checkout:

git bisect reset