CONTRIBUTING.md

Contributing to Plotly.js

Thanks for your interest in contributing to Plotly.js! We are actively looking for diverse contributors, with diverse background and skills.

This document outlines the general way that changes get made to this library and by whom, and then provides specific technical information about how to set up a development environment for doing development and running tests.

Code of Conduct

Please check out our Code of Conduct. Don't tl:dr; it but the general idea is to be nice.

Plotly.js vs Plotly.py and Plotly.R

Plotly.js is a standalone Javascript data visualization library, and it also powers the Python and R modules named plotly in those respective ecosystems (referred to as Plotly.py and Plotly.R, respectively, for clarity). There also exist Plotly.js-powered libraries for other languages such as Julia, Scala, Rust, .NET and even C++!

The basic architecture of Plotly.js is to accept JSON representation of figures that adhere to the figure schema and draw interactive graphical representations of these figures in a browser. Libraries in other languages like Python and R provide idiomatic interfaces for users of those languages to create and manipulate these JSON structures, and arrange for them to be rendered in a browser context by Plotly.js. This means that in many cases, when a Python or R user wishes to add a feature to the library they know as plotly, the relevant changes must be implemented in Plotly.js, in this repo.

How do changes get made to Plotly.js?

A new feature is composed of additions to the schema - adding new attributes, adding entire new trace types, or just adding new values to existing attributes - along with the associated drawing code. This project has a strong commitment to backwards-compatibility, so changing the graphical output for existing schema attributes and values, or changing the default value of an attribute, is generally only done as a mostly-backwards-compatible bug fix, for cases when the current graphical output is incorrect, nonsensical or otherwise very problematic. Non-schema-related features and bug fixes are possible as well, usually around performance, security, bundling, function signatures etc, and generally follow the same principles.

The basic process for adding new features or fixing bugs is as follows. Please note that this is a bit of an idealized outline and that things often don't proceed in a clean/linear fashion and that's ok :)

1. Discussion - A community member or maintainer creates an issue to discuss the use-case for the new feature. This usually entails describing the desired graphical output and discussing how close the current system can get to specifying or drawing such a figure. If the issue is perceived to be a bug, the discussion revolves around understanding how the current behaviour is incorrect or problematic, and how existing users of the system would be impacted by a change in this behaviour.
2. Proposal - If the current system cannot specify or draw such a figure, or if the way to do it is too onerous, a good next step would be to discuss or propose a specific change to the schema: new attributes to be added or new accepted values to new attributes, along with a prose description of the proposed drawing code. If the issue is determined to be a bug rather than a feature, the same type of proposal is required: a definition of which attributes and values will be impacted by the proposed change. A good proposal includes discussion of whether or not existing attributes can be modified rather than adding new attributes and details about which trace types or subplot types are impacted by the change. Note: sometimes community contributors skip this step and go straight to development & review (below), but going through a proposal can help speed along the review process!
3. Iteration - The maintainers of the library or any other interested community member will then give feedback on the proposal, usually focused on consistency with the rest of the schema, and helping define a test plan to further elaborate potential edge cases.
4. Approval - After a number of iterations, the maintainers of the library will generally approve a proposal with an informal "this seems like something we would accept a pull request for" comment in the issue.
5. Development - A community member or maintainer creates a branch and makes the appropriate modifications to the code and tests and opens a pull request. This can be more or less time-consuming and challenging, depending on the nature of the change.
6. Review - The maintainers of the library will review the pull request, working with the original authors to ensure the code is ready for merging. This can involve quite a few iterations and exploration of edge cases, additions of tests etc, but the maintainers are very happy to have outside contributors and will try to make this as painless as possible. Starting out with a previously-discussed proposal (see above) generally helps make this smoother as it reduces the likelihood of overlooked requirements that would prevent a merge.
7. Long-term Maintenance - Once the code is merged, the maintainers of the library will generally look after its maintenance, performance, security, bug fixes etc, although the original author of a feature is always welcome and encouraged to participate in this process!

The Plotly.js Maintainers

The current Plotly.js maintainers are all employees of Plotly (the company) and one of their primary responsibilities is ensuring the process above runs smoothly. It is worth noting that maintainers and non-maintainer Plotly employees all follow the process above: proposing changes, iterating on proposals and eventually developing and reviewing each other's pull requests. As mentioned above, maintainers look after bug fixes, performance, security, documentation and concerns that impact the long-term prospects for this library. In terms of development work, maintainers tend to prioritize issues that do or are likely to impact Plotly customers, as well as on sponsored features or bug fixes. Sponsored work proceeds via the process listed above, albeit with the option of conducting portions of the "discussion" step in a confidential setting if desired. Please note that maintainers are happy and eager to help with community-led pull requests, independent of customer-driven development priorities :)

The Plotly.js Community

The Plotly.js community, construed fairly broadly, includes the maintainers and all users of Plotly.js and associated projects (Plotly.py, Dash, Plotly.R, Chart Studio and many others). The community includes people from any background, domain, affiliation and level of technical expertise, for example (but not limited to!) employees of small or large companies or startups; employees or students of universities or other educational institutions; government employees and contractors; employees and volunteers of non-profits; individual hobbyists etc.

Anyone in the community is encouraged to contribute to every step of the process described above! Creating issues to report bugs or suggest new behaviours is a valuable contribution to this project, as is proposing a concrete set of changes to address issues created by anyone at any time. In the same way, giving feedback on proposals created by anyone in the community is valuable, as is, of course, development and review work. Proposing changes to the documentation of Plotly.js or associated projects is an extremely valuable form of contribution, as is asking or answering questions on our community forum, as it creates a record of a question and discussion, which others can stumble across later and use to further their own work.

Opening issues

Please read the issue guidelines.

Making pull requests

Please read the pull request guidelines.

GitHub labels

We use the following labels to track issues and PRs:

Label	Purpose
type: bug	bug report confirmed by a plotly team member
type: regression	bug that introduced a change in behavior from one version to the next
type: feature	planned feature additions
type: new trace type	subset of type: feature reserved for planned new trace types
type: translation	localization-related tasks
type: performance	performance related tasks
type: maintenance	source code cleanup resulting in no enhancement for users
type: documentation	API doc or attribute description improvements
type: community	issue left open for community input and pull requests
type: duplicate	self-explanatory
type: wontfix	self-explanatory
status: discussion needed	Issue or PR that required discussion among maintainers before moving forward
status: in progress	PRs that required some initial feedback but not ready to merge
status: reviewable	PRs that are completed from the author's perspective
status: on hold	PRs that are put on hold

Development

Prerequisites

• git
• node.js. We recommend using node.js v16.x. Upgrading and managing node versions can be easily done using nvm or its Windows alternatives.
• npm v7.x and up to ensure that the package-lock.json file is used and updated correctly.

Step 1: Fork the plotly.js repository, clone your fork and step into it

git clone --depth 1 git@github.com:<your-GitHub-username>/plotly.js.git
cd plotly.js

Step 2: Switch to a dev branch

# please do not use master or main for your dev branch
git checkout dev-branch-name

Step 3: Install dependencies

npm install

Step 4: Setup test environment

npm run pretest

Step 5: Start the test dashboard

npm start

This command bundles up the source files and opens up a tab in your browser.

Step 6: Open up the console and start developing

A typical workflow is to make some modifications to the source, update the test dashboard, inspect and debug the changes, then repeat. The test dashboard comes bundled with some useful tools while developing - all bundled under the Tabs object:

Method/Property	Description
Tabs.fresh([id])	Creates a fresh graph div and returns it (default id of graph).
Tabs.getGraph([id])	Returns the default or specified graph div.
Tabs.plotMock(mock, [id])	Plots the specified mock (.json extension is not required).
Tabs.snapshot([id])	Creates a png snapshot of the plot and places it below.
Tabs.reload()	Reloads the plotly.js script and will execute Tabs.onReload once completed.
Tabs.onReload()	By default, set to noop but you may set Tabs.onReload to any function you wish. This is useful for replotting a mock or test every time you reload the plotly.js script.
Tabs.purge()	Destroys all plots.

View the source for more info.

Three additional helpers exist that are refreshed every second:

• gd - this is the default plot div
• fullData - shortcut to gd._fullData
• fullLayout - shortcut to gd._fullLayout

There is also a search bar in the top right of the dashboard. This fuzzy-searches image mocks based on their file name and trace type.

Step 7: Regenerate plot-schema in "test" folder then review & commit potential changes

npm run schema

Step 8: Review & commit potential changes made to test/plot-schema.json

If you are editing attribute descriptions or implementing a new feature this file located in the test folder records the proposed changes to the API. Note that there is another plot-schema.json file located in the dist folder, which should only be updated by the maintainers at release time.

IMPORTANT: please do not change and commit any files in the "dist" folder

Step 9: REGL - Review & commit potential changes to precompiled regl shaders

If you are implementing a new feature that involves regl shaders, or if you are making changes that affect the usage of regl shaders, you would need to run

npm run regl-codegen

to regenerate the regl code. This opens a browser window, runs through all traces with 'regl' in the tags, and stores the captured code into src/generated/regl-codegen. If no updates are necessary, it would be a no-op, but if there are changes, you would need to commit them.

This is needed because regl performs codegen in runtime which breaks CSP compliance, and so for strict builds we pre-generate regl shader code here.

Other npm scripts that may be of interest in development

• npm run preprocess: pre-processes the css and svg source file in js. This script must be run manually when updating the css and svg source files.
• npm run watch: starts a watchify file watcher just like the test dashboard but without booting up a server.

Testing

Both jasmine and image tests are run on CircleCI on every push to this repo.

Jasmine tests

Jasmine tests are run in a browser using karma. To run them locally:

npm run test-jasmine

To run a specific suite, use:

npm run test-jasmine -- <suite>

where the <suite> corresponds to the suite's file name as found in test/jasmine/tests/.

You can also test multiple suites at a time, for example:

npm run test-jasmine -- bar axes scatter

which will run tests in the bar_test.js, axes_test.js and scatter_test.js suites.

To turn off the autoWatch / auto-bundle / multiple run mode:

npm run test-jasmine -- <suite> --nowatch

In certain situations, you may find that the default reporting is not verbose enough to pin down the source of the failing test. In this situation, you may wish to use karma-verbose-reporter:

npm run test-jasmine -- <suite> --verbose

For more info on the karma / jasmine CLI:

npm run test-jasmine -- --help
npm run test-jasmine -- --info

Draft new baselines

With docker:

If you prefer using docker each time you need to

docker run -it -v "$(pwd)":/plotly.js circleci/python:3.8.9 bash
# then inside the docker
cd plotly.js
sudo bash .circleci/env_image.sh

Without docker:

Otherwise you may need to install python 3.8 Then upgrade pip if needed

python3 -m pip install --upgrade pip

To install required fonts and tools see this shell script.

Scripts to generate/update new baselines with/without docker:

python3 test/image/make_baseline.py = mock_1 mock_2

Alternatively using npm & node.js (which are not available in the python docker by default)

npm run baseline mock_1 mock_2

Or

npm run baseline mock_*

IMPORTANT: the baseline, test-image and test-export scripts do not bundle the source files before running the image tests. We recommend running npm run watch or npm start in a separate tab to ensure that the most up-to-date code is used. Also if you are adding a new mock, you may need to re-run npm start or npm run watch to be able to find the new mock in the browser. To help ensure valid attributes are used in your new mock(s), please run npm run test-mock or npm run test-mock mock_name(s) after adding new mocks or implementing any new attributes.

If you added new mocks to test/image/mocks folder, to generate draft baselines run

python3 test/image/make_baseline.py = mockFilename1 mockFilename2

Then commit the new baselines and push. Please note that image pixel comparison tests run using circleci/python:3.8.9 docker container. Therefore the final baselines may need updates. This could simply be done by downloading the baselines.tar stored in the ARTIFACTS tab of test-baselines job (if the test failed).

Using the developer console in karma to write/debug jasmine tests

• Click on the DEBUG button
• In the DEBUG RUNNER window, open the console (e.g. with <ctrl-shift-j>)
• Find test file (e.g. with <ctrl-o> + typing the name of the file), look out for "bundled" files with the same name.
• Set debugger on relevant line(s)
• Rerun the test suite by refreshing the page (e.g. with <crtl-r>)

Writing jasmine interaction tests

Keep in mind that the interaction coordinates are relative to the top-left corner of the plot, including the margins. To produce a reliable interaction test, it may be necessary to fix the width, height, margins, X axis range and Y axis range of the plot. For example:

Plotly.newPlot(gd, [{
    x: [1, 1, 1, 2, 2, 2, 3, 3, 3],
    y: [1, 2, 3, 1, 2, 3, 1, 2, 3],
    mode: 'markers'
}], {
    width: 400, height: 400,
    margin: {l: 100, r: 100, t: 100, b: 100},
    xaxis: {range: [0, 4]},
    yaxis: {range: [0, 4]}
});

This will produce the following plot, and say you want to simulate a selection path of (175, 175) to (225, 225):

Repo organization

• Distributed files are in dist/
• CommonJS require-able modules are in lib/
• Sources files are in src/
• Build and repo management scripts are in tasks/
• All tasks can be run using npm run-script
• Tests are test/, they are partitioned into image and jasmine tests
• Test dashboard and image viewer code is in devtools/
• Built files are in build/ (the files in here are git-ignored, except for plotcss.js)

Trace module design

The trace modules (found in src/traces) are defined as plain objects with functions and constants attached to them in an index file (e.g. src/traces/scatter/index.js). The trace modules are "registered" undo the Registry object (found in src/registry.js) using Plotly.register (as done in the index files in dist/).

The trace module methods are meant to be called as part of loops during subplot-specific (e.g. in plots/cartesian/index.js) and figure-wide (e.g. in plots/plots.js) subroutines. That way, the subroutines work no matter which trace modules got registered.

All traces modules set:

• _module.name: name of the trace module as used by the trace type attribute.
• _module.basePlotModule: base plot (or subplot) module corresponding to the trace type (e.g. scatter links to the Cartesian base plot module, scatter3d links to gl3d).
• _module.attributes: JSON-serializable object of attribute declarations. This object is used to generate the plot-schema JSON.
• _module.supplyDefaults: Takes in input trace settings and coerces them into "full" settings under gd._fullData. This one is called during the figure-wide Plots.supplyDefaults routine. Note that the supplyDefaults method performance should scale with the number of attributes (not the number of data points - so it should not loop over any data arrays).
• _module.calc: Converts inputs data into "calculated" (or sanitized) data. This one is called during the figure-wide Plots.doCalcdata routine. The calc method is allowed to scale with the number of data points and is in general more costly than supplyDefaults. Please note that some edit pathways skip Plots.doCalcdata (as determined by the editType flags in the attributes files).
• _module.plot: Draws the trace on screen. This one is called by the defined basePlotModule.

Other methods used by some trace modules:

• _module.categories: list of string identifiers used to group traces by behavior. Traces that have a given category can then be detected using Registry.traceIs
• _module.layoutAttributes: JSON-serializable object of attribute declarations coerced in the layout (e.g. barmode for bar traces)
• _module.supplyLayoutDefaults: Defaults logic for layout attributes.
• _module.crossTraceDefaults: Defaults logic that depends on input setting of multiple traces.
• _module.crossTraceCalc: Computations that depend on the data of multiple traces.
• _module.colorbar: Defines the colorbar appearance for traces that support it.
• _module.hoverPoints: Point-picking logic called during hover.
• _module.selectPoints: Polygon-containing logic called during selections.
• _module.style: Sometimes split from _module.plot where _module.plot only draws the elements and _module.style styles them.
• _module.styleOnSelect: Optimization of _module.style called during selections.
• _module.convert: Sometimes separated from _module.plot or _module.calc to convert the plotly.js settings to another framework e.g. to gl-plot3d for gl3d traces, to mapbox-gl from mapbox traces. This split can make the logic easier to test. If you make a convert, you should call it from either calc or plot.

Coding style

Check if ok, with npm run lint

• See eslintrc and the eslint list of rules for more details.
• Rules listed in the eslintrc file with the ignore flag 0 are the recommended rules for new code added.