How to contribute

Getting help

Community discussion, questions, and informal bug reporting is done on the
discuss.CodeMirror forum.

Submitting bug reports

The preferred way to report bugs is to use the
GitHub issue tracker. Before
reporting a bug, read these pointers.

Note: The issue tracker is for bugs, not requests for help. Questions
should be asked on the
discuss.CodeMirror forum instead.

Reporting bugs effectively

CodeMirror is maintained by volunteers. They don't owe you anything, so be
polite. Reports with an indignant or belligerent tone tend to be moved to the
bottom of the pile.
Include information about the browser in which the problem occurred. Even
if you tested several browsers, and the problem occurred in all of them,
mention this fact in the bug report. Also include browser version numbers and
the operating system that you're on.
Mention which release of CodeMirror you're using. Preferably, try also with
the current development snapshot, to ensure the problem has not already been
fixed.
Mention very precisely what went wrong. "X is broken" is not a good bug
report. What did you expect to happen? What happened instead? Describe the
exact steps a maintainer has to take to make the problem occur. We can not
fix something that we can not observe.
If the problem can not be reproduced in any of the demos included in the
CodeMirror distribution, please provide an HTML document that demonstrates
the problem. The best way to do this is to go to
jsbin.com, enter it there, press save, and
include the resulting link in your bug report.

Contributing code

Note that we are not accepting any new addons or modes into the main
distribution. If you've written such a module, please distribute it as
a separate NPM package.

Make sure you have a GitHub Account
Fork CodeMirror
(how to fork a repo)
Make your changes
If your changes are easy to test or likely to regress, add tests.
Tests for the core go into test/test.js, some modes have their own
test suite under mode/XXX/test.js. Feel free to add new test
suites to modes that don't have one yet (be sure to link the new
tests into test/index.html).
Follow the general code style of the rest of the project (see
below). Run bin/lint to verify that the linter is happy.
Make sure all tests pass. Visit test/index.html in your browser to
run them.
Submit a pull request
(how to create a pull request).
Don't put more than one feature/fix in a single pull request.

By contributing code to CodeMirror you

agree to license the contributed code under CodeMirror's MIT
license.
confirm that you have the right to contribute and license the code
in question. (Either you hold all rights on the code, or the rights
holder has explicitly granted the right to use it like this,
through a compatible open source license or through a direct
agreement with you.)

Coding standards

2 spaces per indentation level, no tabs.
Note that the linter (bin/lint) which is run after each commit
complains about unused variables and functions. Prefix their names
with an underscore to muffle it.
CodeMirror does not follow JSHint or JSLint prescribed style.
Patches that try to 'fix' code to pass one of these linters will be
unceremoniously discarded.