Contributing to the RxPlayer

Issues and new features

If you detect a problem with the RxPlayer, or if you desire a new feature, please first open an issue on the github's repository. We'll try to acknowledge it as soon as possible.

If that issue is not already worked on, we will usually accept pull requests. Those have to follow the conventions defined below.

Important code concepts

Code documentation

We try to put README.md files inside every significant directories inside /src to provide a global architecture documentation of that directory specifically.

You can try to start understanding a piece of RxPlayer code by navigating to that file. Understand that the documented behavior may be out of date (in which case you're welcome to update it or open an issue) though even in that case, it is a good starting point to understand the directory's role. Likewise, don't forget to update it if a change you made to the code necessitates a documentation change.

Also, for a more exhaustive approach to the documentation of the project's file organization, you can look at FILES.md.

When renaming or deleting functions, classes or variables

When Refactoring/Renaming, make sure to grep any of the renamed class / function / variable's name as they may also be referenced in documentation and code comments. Same thing for a directory or file name.

If the name is hard to grep (e.g. the name is too generic and thus has too many false positives), you can generally reduce the area to comments in the same file and documentation files in the same directory.

features object

Some files should not be imported directly but only be accessed by going through the features object exported at /src/features. This is to reduce bundle size when an application doesn't need all of the RxPlayer's features.

Multithreading

Some parts of the code are intented to be runnable in a WebWorker. In that environment some API, more specifically DOM-related API, are not available directly (if some interaction with the DOM is needed, it will have to go through an asynchronous postMessage round-trip).

Whether the code needs to be runnable or not in a WebWorker is generally documented in the README.md of concerned directories.

Code style

Linting

The code style in src is automatically checked by a "linter", eslint.

It basically follows those principles:

  • 2 spaces indentation
  • 90 columns maximum
  • readability and being explicit is generally better than performance and being smart

You can easily check if you followed our style rules by calling npm run lint.

You can also check the style of the demo page (in the demo directory) by calling npm run lint:demo, or the style of the test files (in the tests directory) by calling npm run lint:tests.

Types

We try to be as strict as possible with types:

  • the any type should be avoided

  • the as TypeScript keyword, used for type casting, should also be avoided as much as possible.

This is to be sure we can detect as much as possible type errors automatically with TypeScript.

type and interface typing

TypeScript's type and interface should all be named beginning with the letter I, for easier identification purposes*:

interface IMyObject {
  someKey: string;
}

type IStringOrNumber = string |
                       number;

enums and const enums, which have the particularity in TypeScript of actually having an influence on the outputed code, do not follow this rule however (because those are not just types erased during transpilation):

enum MyEnum {
  ValueA = 1,
  ValueB = 2,
}

const enum MyConstEnum {
  Value1 = 1,
  Value2 = 2,
}

*We know that this rule is a controversial subject amongst TypeScript developpers, yet we still decide to enforce it for now.

Forbidden functions and classes

Some native functions, methods or classes should never be used to ensure compatibility with most browsers. To work around those, we usually rely on "ponyfills" which are JavaScript re-implementations.

This concerns the following static methods:

  • Object.assign: use src/utils/object_assign.ts instead
  • Object.values: use src/utils/object_values.ts instead

And the following methods:

  • Array.prototype.includes: use src/utils/array_includes.ts instead
  • Array.prototype.find: use src/utils/array_find.ts instead
  • Array.prototype.findIndex: use src/utils/array_find_index.ts instead
  • String.prototype.startsWith: use src/utils/starts_with.ts instead
  • String.prototype.substr: use String.prototype.substring instead
  • NodeList.prototype.forEach: use a regular for loop instead
  • Promise.prototype.finally: Use then or both then and catch of that Promise's methods instead.

The demo page

Building the demo and serving it

You might want to quickly test your code modification(s) on a real use case.

For those types of need, we developped two demo pages:

  • the full demo page, which is also the one used to showcase the player.

    This demo has a user-friendly interface and allow the most frequent API interactions.

    It also exposes both the RxPlayer class through window.RxPlayer and the rxPlayer instance through window.rxPlayer - both in the global scope. You can thus open a debugger/inspector in your favorite browser to exploit directly the player's API.

  • the standalone demo page, which is just a <video /> tag linked to a RxPlayer instance.

    In this demo too, window.RxPlayer and window.rxPlayer link to the RxPlayer class and the rxPlayer instance respectively.

To use the full demo page, you can build it and run a local HTTP server on the port 8000 by running the following npm script.

npm run start

To use the standalone demo page, you can build it and run a local HTTP server on the port 8001 by running the following npm script.

npm run standalone

Both will detect when the RxPlayer's files (or even the demo files) are updated and perform a new build when that's the case. In that way, the server will always serve the last local version of the code. Note however that hot-reload is not enabled currently, you'll have to refresh the page yourself.

Serving the demo page through HTTPS

You might want to serve the demo via HTTPS. This is for example needed to be able to play encrypted contents in Chrome.

Thankfully, we have an npm script which generates a local self-signed certificate with the help of openssl:

npm run certificate

You can then run the same demo script defined previously. The full demo will now serve HTTPS through the port 8443 and the standalone demo through the port 8444. Both still serve HTTP on the same ports than before.

Note that such self-signed certificates are usually (rightfully) considered suspicious by web browsers. As such, you might first encounter a warning screen when going to one of the demo pages in HTTPS. In most browsers, you can however safely ignore that warning.

Creating a commit

Checks

Every commits in a PR should pass our quick checks (linter and TypeScript check). To check if that's the case, you can run locally the check script by calling npm run check.

The test suite

Unit tests

Unit tests test function implementations. Mostly to check if they give a sane output for every input given.

Writing unit tests for new code is encouraged.

Unit tests are written in a __tests__ directory, itself created in the same directory that the code it tests.

They are written and run with the help of the Jest library and are named the following way: filename_containing_the_function_tested.test.ts.

To understand how to create a new test file, you can take inspiration from the current unit tests.

Integration tests

What we call integration tests are tests testing the entire API of the RxPlayer.

New integration tests are not required when a new code is added. Just make sure that all those tests pass before doing a pull request by running: npm run test:integration.

It you want to improve our integration tests, you are welcome to do so. Those are wrote in tests/integration with the help of the Mocha, Chai and Sinon libraries.

We also use a homemade library and server to serve media contents to our tests. If you want to know how it works, we invite you to rely on the already created tests and to read the corresponding files.

Memory tests

Memory tests replicate simple scenarios and try to detect memory leaks.

You can also help us improving our memory tests. Those are written in test/memory. The testing stack used is Mocha, Chai and Sinon.

Documentation

The documentation is written in the doc directory, at the root of the project.

The content of doc/generated contains an HTML version of the Markdown files written in the other directories. It is automatically generated from those by calling the doc script through npm run doc.

Opening a pull request

Which branch to merge to

Pull requests for bug fixes, new tests or documentation should be done on the stable branch.

Pull requests for new features and breaking changes will have to be performed on the dev branch.

If you don't know on which branch to do a pull request, please open it on dev, we will know how to redirect it to the right one.

Contributing to the RxPlayer

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