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Contributing to Node.js

Code of Conduct

The Code of Conduct explains the bare minimum behavior expectations the Node Foundation requires of its contributors. Please read it before participating.

Issue Contributions

When opening new issues or commenting on existing issues on this repository please make sure discussions are related to concrete technical issues with the Node.js software.

For general help using Node.js, please file an issue at the Node.js help repository.

Discussion of non-technical topics including subjects like intellectual property, trademark and high level project questions should move to the Technical Steering Committee (TSC) instead.

Code Contributions

The Node.js project has an open governance model and welcomes new contributors. Individuals making significant and valuable contributions are made Collaborators and given commit-access to the project. See the GOVERNANCE.md document for more information about how this works.

This document will guide you through the contribution process.

Step 1: Fork

Fork the project on GitHub and check out your copy locally.

$ git clone git@github.com:username/node.git
$ cd node
$ git remote add upstream git://github.com/nodejs/node.git

Which branch?

For developing new features and bug fixes, the master branch should be pulled and built upon.

Respect the stability index

The rules for the master branch are less strict; consult the stability index for details.

In a nutshell, modules are at varying levels of API stability. Bug fixes are always welcome but API or behavioral changes to modules at stability level 3 (Locked) are off-limits.

Dependencies

Node.js has several bundled dependencies in the deps/ and the tools/ directories that are not part of the project proper. Any changes to files in those directories or its subdirectories should be sent to their respective projects. Do not send a patch to Node.js. We cannot accept such patches.

In case of doubt, open an issue in the issue tracker or contact one of the project Collaborators. Especially do so if you plan to work on something big. Nothing is more frustrating than seeing your hard work go to waste because your vision does not align with the project team. (Node.js has two IRC channels: #Node.js for general help and questions, and #Node-dev for development of Node.js core specifically.

For instructions on updating the version of V8 included in the deps/ directory, please refer to the Maintaining V8 in Node.js guide.

Step 2: Branch

Create a branch and start hacking:

$ git checkout -b my-branch -t origin/master

Step 3: Commit

Make sure git knows your name and email address:

$ git config --global user.name "J. Random User"
$ git config --global user.email "j.random.user@example.com"

Add and commit:

$ git add my/changed/files
$ git commit

Writing good commit logs is important. A commit log should describe what changed and why. Follow these guidelines when writing one:

  1. The first line should be 50 characters or less and contain a short description of the change. All words in the description should be in lowercase with the exception of proper nouns, acronyms, and the ones that refer to code, like function/variable names. The description should be prefixed with the name of the changed subsystem and start with an imperative verb, for example, "net: add localAddress and localPort to Socket".
  2. Keep the second line blank.
  3. Wrap all other lines at 72 columns.

A good commit log can look something like this:

subsystem: explain the commit in one line

Body of commit message is a few lines of text, explaining things
in more detail, possibly giving some background about the issue
being fixed, etc. etc.

The body of the commit message can be several paragraphs, and
please do proper word-wrap and keep columns shorter than about
72 characters or so. That way `git log` will show things
nicely even when it is indented.

The header line should be meaningful; it is what other people see when they run git shortlog or git log --oneline.

Check the output of git log --oneline files_that_you_changed to find out what subsystem (or subsystems) your changes touch.

If your patch fixes an open issue, you can add a reference to it at the end of the log. Use the Fixes: prefix and the full issue URL. For other references use Refs:. For example:

Fixes: https://github.com/nodejs/node/issues/1337
Refs: http://eslint.org/docs/rules/space-in-parens.html
Refs: https://github.com/nodejs/node/pull/3615

Step 4: Rebase

Use git rebase (not git merge) to sync your work from time to time.

$ git fetch upstream
$ git rebase upstream/master

Step 5: Test

Bug fixes and features should come with tests. Add your tests in the test/parallel/ directory. For guidance on how to write a test for the Node.js project, see this guide. Looking at other tests to see how they should be structured can also help.

To run the tests on Unix / OS X:

$ ./configure && make -j4 test

Windows:

> vcbuild test

(See the BUILDING.md for more details.)

Make sure the linter is happy and that all tests pass. Please, do not submit patches that fail either check.

Running make test/vcbuild test will run the linter as well unless one or more tests fail.

If you want to run the linter without running tests, use make lint/vcbuild jslint.

If you are updating tests and just want to run a single test to check it, you can use this syntax to run it exactly as the test harness would:

$ python tools/test.py -v --mode=release parallel/test-stream2-transform

You can run tests directly with node:

$ ./node ./test/parallel/test-stream2-transform.js

Remember to recompile with make -j4 in between test runs if you change core modules.

Step 6: Push

$ git push origin my-branch

Go to https://github.com/yourusername/node and select your branch. Click the 'Pull Request' button and fill out the form.

Pull requests are usually reviewed within a few days.

Step 7: Discuss and update

You will probably get feedback or requests for changes to your Pull Request. This is a big part of the submission process, so don't be disheartened!

To make changes to an existing Pull Request, make the changes to your branch. When you push that branch to your fork, GitHub will automatically update the Pull Request.

You can push more commits to your branch:

$ git add my/changed/files
$ git commit
$ git push origin my-branch

Or you can rebase against master:

$ git fetch --all
$ git rebase origin/master
$ git push --force-with-lease origin my-branch

Or you can amend the last commit (for example if you want to change the commit log).

$ git add any/changed/files
$ git commit --amend
$ git push --force-with-lease origin my-branch

Important: The git push --force-with-lease command is one of the few ways to delete history in git. Before you use it, make sure you understand the risks. If in doubt, you can always ask for guidance in the Pull Request or on IRC in the #node-dev channel.

Feel free to post a comment in the Pull Request to ping reviewers if you are awaiting an answer on something. If you encounter words or acronyms that seem unfamiliar, check out this glossary.

Note that multiple commits often get squashed when they are landed (see the notes about commit squashing).

Step 8: Landing

In order to get landed, a Pull Request needs to be reviewed and approved by at least one Node.js Collaborator and pass a CI (Continuous Integration) test run. After that, as long as there are no objections from a Collaborator, the Pull Request can be merged. If you find your Pull Request waiting longer than you expect, see the notes about the waiting time.

When a collaborator lands your Pull Request, they will post a comment to the Pull Request page mentioning the commit(s) it landed as. GitHub often shows the Pull Request as Closed at this point, but don't worry. If you look at the branch you raised your Pull Request against (probably master), you should see a commit with your name on it. Congratulations and thanks for your contribution!

Additional Notes

Commit Squashing

When the commits in your Pull Request get landed, they will be squashed into one commit per logical change, with metadata added to the commit message (including links to the Pull Request, links to relevant issues, and the names of the reviewers). The commit history of your Pull Request, however, will stay intact on the Pull Request page.

For the size of "one logical change", 0b5191f can be a good example. It touches the implementation, the documentation, and the tests, but is still one logical change. In general, the tests should always pass when each individual commit lands on the master branch.

Getting Approvals for Your Pull Request

A Pull Request is approved either by saying LGTM, which stands for "Looks Good To Me", or by using GitHub's Approve button. GitHub's Pull Request review feature can be used during the process. For more information, check out the video tutorial or the official documentation.

After you push new changes to your branch, you need to get approval for these new changes again, even if GitHub shows "Approved" because the reviewers have hit the buttons before.

CI Testing

Every Pull Request needs to be tested to make sure that it works on the platforms that Node.js supports. This is done by running the code through the CI system.

Only a Collaborator can request a CI run. Usually one of them will do it for you as approvals for the Pull Request come in. If not, you can ask a Collaborator to request a CI run.

Waiting Until the Pull Request Gets Landed

A Pull Request needs to stay open for at least 48 hours (72 hours on a weekend) from when it is submitted, even after it gets approved and passes the CI. This is to make sure that everyone has a chance to weigh in. If the changes are trivial, collaborators may decide it doesn't need to wait. A Pull Request may well take longer to be merged in. All these precautions are important because Node.js is widely used, so don't be discouraged!

Check Out the Collaborator's Guide

If you want to know more about the code review and the landing process, you can take a look at the collaborator's guide.

Developer's Certificate of Origin 1.1

By making a contribution to this project, I certify that:

  • (a) The contribution was created in whole or in part by me and I have the right to submit it under the open source license indicated in the file; or

  • (b) The contribution is based upon previous work that, to the best of my knowledge, is covered under an appropriate open source license and I have the right under that license to submit that work with modifications, whether created in whole or in part by me, under the same open source license (unless I am permitted to submit under a different license), as indicated in the file; or

  • (c) The contribution was provided directly to me by some other person who certified (a), (b) or (c) and I have not modified it.

  • (d) I understand and agree that this project and the contribution are public and that a record of the contribution (including all personal information I submit with it, including my sign-off) is maintained indefinitely and may be redistributed consistent with this project or the open source license(s) involved.