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Contribution guidelines

Firstly, thanks for taking an interest in these projects!

There're many ways you can contribute, help to improve these projects and spread the word. This doc describes some loose guidelines for some of them.

Usage questions & issues

Join our discussions

We have a (still new) discussion forum here on Github, (hopefully soon again) the fastest way to get some answers to any burning questions and where we generally share & discuss feedback/ideas/interesting things loosely related to this project. Come and say Hi!

(In the past (2018-2022), we also had a Discord, but you can read more about its fate in this forum post...)

Submit an issue

In many cases, it might be better to submit an issue here on GitHub, especially if you've discovered some kind of bug and/or want to propose new features etc., which require longer discussion. I'd also encourage using the issue tracker for any topic which might be beneficial to know/discover for other users in the future (much like a forum), since this format & discussion has more longevity/discoverability than a Discord channel.

When submitting an issue, please follow the instructions in the "new issue" template.

When running into code troubles, please also try to include a minimal reproducible example. If the example is too large for including in the issue, please create a gist or repo and add a link to it.

Documentation, examples & advocacy

Due to the wide scope of this project, documentation is still sparse in some areas, so any contributions in the form listed below are very welcome. I primarily can only work on this project in my spare time, so have to balance between adding new features (always my priority) & documentation whenever I can.

Please also see further information about doc strings in the source code below.

Changes to readme files

The readme files for all packages are generated from their respective templated versions ( files). Please only ever edit the template and then re-generate the actual readme like so:

cd umbrella
yarn workspace<package-name> run doc:readme

Wiki additions, blog posts, examples

The wiki of this repo is still pretty barebones, however adding some gallery, FAQs, tutorials, best practice tips, feature ideas/roadmaps and a collection of links to blog posts, 3rd party examples, etc. is planned. If you have anything to contribute (or have already done so elsewhere), please do get in touch.

Small, standalone examples in the repo

"Learning by example" has been my life's motto. The ~85 examples included in the repo are each focused on specific features and kept quite lowkey for reasons of simplicity. Since many of the projects are meant to be integrated with other 3rd party projects, I'm always on the lookout for similar small demos showcasing these integrations (e.g. w/ React, WebGL, SVG, etc.)

The repo contains a generator bash script to create a new example project skeleton in the repo's /examples dir. Use it like below (and make sure the name isn't already taken :)

cd umbrella
scripts/make-example my-example

cd examples/my-example

Currently, it's recommended to install Parcel globally for running the example. Please consult the example build instructions in the wiki.

FWIW I usually launch examples from the repo root via a subshell:

(cd examples/webgl-msdf && yarn start)

If you choose to add a new example this way (and not elsewhere on the interweb), please also read the next section...

Contributing code

IMPORTANT: To avoid misunderstandings or disappointment, please always first submit an issue discussing any new feature or large refactoring before starting to code and submitting PRs. For small bug fixes or new examples, it's usually fine without, though. I'm not trying to complicate things, but it's always a good idea to first talk about larger contributions and there're also various (sometimes still unpublished) feature branches, incl. some existing WIP relevant to your issue/proposal...

Fork it

git clone
cd umbrella

# Installs all dev deps & builds all packages
yarn build

Create a feature branch

Creating feature branches is only needed for adding new code or larger fixes/refactoring. If you're only updating some docs or other minor fixes you can work on your own develop branch directly...

Always use develop as base branch, which also is the default branch of this repo...

git checkout -b feature/my-feature develop

This repo is using the git-flow branching model and all new development should be done on feature branches based off the current develop branch. PR's submitted directly against the master branch WILL be refused (with a few exceptions).

With the git-flow CLI tool installed, you can also run:

git-flow feature start my-feature

Commit your changes

git commit -am 'feat(module): description'

Please do use the Conventional Commits convention for your commit messages. This format is used to generate changelogs and ensures consistency and better filtering. Since this is a mono repository the convention ensures commit messages can be easily mapped to their sub-project. Also, see existing commits for reference (example).

The Conventional Commits classifiers/prefixes used in this project are:

  • feat - new feature
  • fix - bug fixes
  • refactor - refactoring
  • test - testing related
  • perf - any type of optimization (not just performance)
  • build - build/dependency related updates
  • docs - documentation related only (e.g. readme, doc strings...)
  • chore - unclassified chores
  • minor - usually fixed typos (unless it qualifies as bug fix)

Run & add tests

I'm heavily using the Node REPL during development and do much of my testing as part of that workflow. Still, I'm aware that this is no full replacement for a large suite of tests, therefore most packages do have a varying (but growing) number of unit tests. If you're adding a new feature (or think you've fixed a bug), please add some related tests (if possible) too for extra brownie points. Either add a new file under a project's /test dir or add/edit one of the existing test cases in there.

Tests can be run via:

yarn workspace<package-name> run test

# or
(cd packages/<package-name> && yarn test)

# or all tests (from repo root)

yarn test # also builds all packages first

yarn test:only # assumes all packages have been build already

Push to your feature branch

git push origin feature/my-feature

Create new Pull Request

Go to your fork on GH and create a PR. If there's no prior issue related to the PR, please make sure you explain its purpose.

Code style guide

Project layout

Unless the package is very small, all larger ones in this repo share this pattern:

  • /src/index.ts - only used for re-exports
  • /src/api.ts - interfaces, enums, type aliases & module global consts definitions
  • /test - Mocha unit tests

In larger packages (e.g. topically related files are grouped in sub-folders under /src.


To encourage small(er) file sizes of production artifacts, most source files are organized to only contain a small number of related functions/classes. Package internal imports MUST always refer to the actual source file, whereas imports from other packages MUST only use the package name. This is because of the way each package is built and output in 3 different module formats (ES6, CJS, UMD).

Sorted imports

Please ensure you're updating the list of imports in changed files to be sorted by package name. In VSCode it's as easy as hitting Shift + Alt + O or choosing "Organize imports" from the command palette.

No default exports

Nuff said. They're potentially problematic in terms of refactoring and too cause inconsistencies compared to the above named import pattern.

No 3rd party dependencies

This does NOT apply to examples, only code in source packages

Unless absolutely warranted. Yes, this is somewhat a case of Not-Invented-Here, but here done for reasons of sanity & clarity, not to prove a point. If you plan to submit code with 3rd party deps, please get in touch first and explain why it's necessary (in your humble opinion).

Intra-repo dependencies

Please use your best judgment before introducing a new dependency on another package within this repo and remember that even though these packages are developed under one "umbrella", the aim is NOT to form a tightly coupled framework. In general, it's absolutely fine to depend on any of the "low level" packages, e.g.

...since these are purely existing for providing general plumbing and are primarily meant for wide re-use. However, consider if adding a dependency on one of the larger packages (e.g., is absolutely required / beneficial.

If in doubt, please ask first...

No exported const enums

It has been brought to my attention (thanks to @Bnaya) that exported const enums negatively interfere with some downstream workflows related to Babel transpilation and TypeScript's isolatedModules compilation feature. For that reason, that latter option is now enabled for all packages and exported const enums are NOT to be used anymore in this project. The only exceptions are packages where const enums are used internally. For all others, we have reverted to using normal enums, but might introduce alternatives in the future...

Arrow functions preferred

Again, this is highly subjective - but unless a function requires overrides, please use arrow functions for succinctness and avoidance of potential scoping issues.

const add = (a: number, b: number) => a + b;

// vs.

function add(xs: Iterable<number>): number;
function add(a: number, b: number): number;
function add(a: any, b?: number): number {
    if (typeof a === "number") {
        return a + b;
    let sum = 0;
    for (let x of a) {
        sum += x;
    return sum;

Function / ctor arguments

If a function or constructor takes multiple optional arguments, please consider using a typed options argument instead of positional args. This pattern is used in various existing packages already and involves introducing a new interface for the options (see naming conventions), e.g.:

import type { Fn, Comparator } from "";

// type arg is optional / context specific
interface SortOpts<T> {
     * Key extractor
    key: Fn<A, number>;
     * Optional comparator
    cmp?: Comparator<number>;

const sort = <T>(coll: T[], opts: FooOpts<T>) => {
    const cmp = opts.cmp || ((a, b) => a - b);
    return coll.sort((a, b) => cmp(opts.key(a), opts.key(b)));

Naming conventions

These are not fully set in stone, but there's been a recent effort underway to unify naming conventions & patterns for several aspects/groups of functions / types:

General naming

Prefer short (though not cryptic) names over highlyDescriptiveLongCompoundName style variable (or function) names, which completely destroy formatting and resulting code comprehension (a kind of counter-effect of the supposedly more descriptive longer name).

  • Packages: lower-kebab-case
  • Classes: capitalized CamelCase
  • Functions, class methods & Variables: lower-initial camelCase
  • Exported constants: UPPER_SNAKE_CASE
  • Enums:
    • type name itself: capitalized CamelCase
    • constants: UPPER_SNAKE_CASE


If the interface is primarily defining a set of operations, we prefix its name with I to distinguish it from a data descriptor.

interface IBind<T> {
    bind(opts: T): boolean;
    unbind(): boolean;

interface BindOpts {
    texID: string;
    texOpts: TextureOpts;

interface TextureOpts {
    filter: Filter;
    wrap: WrapMode;

Factory functions

Not (yet?) used consistently, but in order to encourage a more function driven coding style (regardless of using some OOP concepts internally), functions which create some form of resource/object/class instance should be using the def prefix (inspired by Clojure and other Lisps). For classes, this means adding a factory function delegating to the class constructor and potentially performing additional preparation tasks. This is not just done for stylistic reasons, but also to work around the limitation of not being able to provide overrides for class ctors (however function overrides are supported, of course).

 * Returns a new {@link Particle} instance with given initial position
 * @param pos - initial position
export const defParticle = (pos: Vec) => new Particle(pos);

export class Particle {
    constructor(public pos: Vec) {}

// usage

const particles = [[0, 0], [1, 0], [2, 0]].map(defParticle);

// vs

const particles = [[0, 0], [1, 0], [2, 0]].map((p) => new Particle(p));

There're other situations (e.g. or where this naming convention is not making much sense, but the above is the currently preferred approach. Not dogma!

Standalone factory functions are also favored over static class methods (though some are currently still in use, soon to be refactored).

Options objects

As stated above, interfaces describing a collection of optional function / ctor arguments should always be suffixed with Opts.

Doc strings

In 2019 we refactored doc strings across all 120+ packages to become an early adopter of the TSDoc documentation standard and API extractor toolchain, both developed by Microsoft.

Whilst that tooling is still WIP, please familiarize yourself with the available documentation tags and use the format when adding/updating doc strings.

There's been some initial work done on generating a better documentation site than the current, but currently on hold until the TSDoc standard is finalized / stable...

More discussion & context can be found in this issue.


All source code is to be formatted with Prettier and a config file is included in the repo root.

If you're using VSCode, I recommend installing the Prettier extension and configuring it to auto-format on save.

For others, the important rules are:

  • 4 spaces, no tabs (sorry!)
  • semicolons enabled
  • unix line breaks


This project has been in development since early 2016 (some packages even older). If you would like to support the continued development & ever-increasing maintenance effort of this project, please consider a financial contribution (anything helps!) via any of the following channels: