Contributing Guide#

Thanks for your interest in contributing to thebe, your contributions are welcome and appreciated 🎉. This page contains some information to help you get started.


thebe was recently called thebelab, so you may see mentions of thebelab scattered throughout the repository. Feel free to flag these and suggest we rename them to thebe.

Contributing guide#

See the ExecutableBooks developer guidelines for conventions and practices around developing thebe. However, note that some practices, such as creating releases, may be different because thebe is primarily an Javascript (npm) package rather than a Python package.

Repository structure#

thebe is primarily written in Javascript, and structured as an NPM package.

  • src/ contains the code and assets that make up thebe. This is what you’ll edit to make changes to the project.

  • examples/ provides a few HTML examples of how thebe can be used. It is mostly for documentation

Set up a development environment#

In order to get Thebe running locally, you’ll need to have Node installed on your system.

Minimum requirements are:

  • nodejs v15.0 or greater

  • npm v6.0 or greater

  • yarn v1.22 or greater

You can install it in several ways, the most common being:

conda install -c conda-forge nodejs

Once installed, also install yarn which is what you will run in order to run Thebe locally.

npm install -g yarn

Next, clone the repository and install the required dependencies:

git clone
cd thebe
yarn install

This will install all dependencies needed to run thebe (specified in package.json). By default, yarn install will also have created a production build in lib

If you are using npm v7 you may encounter Peer Dependency Errors see comments below to resolve these.


Using yarn install will ensure that you install the latest tested dependencies, and will not make any unintentional local upgrades. yarn uses npm under the hood, please do not use npm install directly to install dependencies.

Peer Dependency Errors#

Due to recent changes in npm as of v7 peer dependency issues are flagged as critical errors. However, many projects have not yet resolved these issues in their code base, this means that a project’s co-dependencies can prevent installation of a package. This is a know issue, to resolve this there are two options:

  1. Downgrade npm to v6

  npm install -g npm@6
  1. Set the legacy-peer-deps option in your local environment

  npm config set legacy-peer-deps true

Build and demo thebe locally#

To use your local copy of thebe (e.g., if you make any changes to the src/ folder), you can run a local build and serve a sample web page. To do so, run:

yarn run build:watch

This will build thebe/ locally (including any changes you’ve made to the source code).

You can now demo the latest thebe/ changes by opening the file at development/binder.html. Open this file to see Thebe running.

The content of development/binder.html is a simple HTML page that demonstrates Thebe functionality. You can edit it to test out new features or configurations.

Running the yarn run develop command will start a watch on the source code, building with webpack and will serve it along with development/binder.html. As you change the code in src/, the javascript will automatically be re-built, but you’ll be required to refresh the page.

Using a local kernel#

development/binder.html will connect to a public binder instance which can be slow.

For faster development and easy control over the python environment available to Jupyter is run yarn run develop:local instead.

This will serve the file from development/local.html which will attempt to connect to a local Jupyter kernel.

You will need to have Jupyter running with the expected authentication token for this to work. i.e.

jupyter notebook \
  --NotebookApp.token=thebe-test-secret \

Committing changes#

Thebe uses code autoformatting so you don’t need to worry about style lint, so whenever you are ready to commit changes run yarn run fmt to autoformat the javascript. You can put this script in .git/hooks/pre-commit:

if [[ -f package.json ]]; then
    yarn run fmt

to run auto-formatting prior to each commit.

Testing Thebe#

You can test manually, interactively by running yarn run develop to open and serve development.html with the current build of thebe. This allows you to develop and test something that you are implementing locally, for example a version of your page where you intend to use the library.

When modifying the thebe library manually testing is still required as automated test coverage is limited. Changes to thebe can tested for regression in two ways:

  1. via the html examples in the docs/_static/html_examples/ folder

  2. via the sphinx documentation in docs - see the section on Building the Docs below. When testing all thebe examples implemented in the documentation should work.

Testing HTML examples#

While most of the html examples can be run as files (file://) it’s better to serve the examples using a local server where we can expect all to work, this can be done by:

  yarn serve:examples

Running automated tests#

There are two types of automated test environment in place in thebe both using the Jest testing library. These are:

  1. a standard javascript testing setup for unit / component level testing of the thebe library. These can be run using yarn run test or yarn run test:watch and test code is located in the test folder.

  2. e2e style tests using jest + puppeteer that can be run yarn run test:e2e or yarn run test:e2e:watch and test code is located in the e2e folder.

Alternately, you can push your changes to GitHub and let the tests run automatically via GitHub Actions.

TODO: get testing infrastructure to a point where we can reasonably request tests for new features.

Adding unit tests#

Unit style tests work by loading the thebe library or part of it in javascript; mocking inputs and/or dependencies, executing a function and asserting on outputs of mocks. A good first example to look at is tests/bootstrap.spec.js. This test:

  • loads thebe js code import * as thebelab from "../src/thebelab";

  • manipulates the dom to prep the test (via built in JSDOM)

  • calls the thebe.bootstrap() function

  • checks for expected behaviour

If you are new to Jest check their getting started, mocking and expect assertion api docs.

Adding e2e Tests#

e2e style tests are achieved using Puppeteer a headless chrome api that can be used to load a page complete with thebe scripts, allowing full execution as though it was in an end user browser and then assertion of end state.

Adding new e2e tests involves: (see e2e/readonly.test.js for an example)

  • creating a test html page that load and uses thebe, placing this in the e2e/fixtures/HTML folder

  • load the fixture page at the start of your test

beforeAll(async () => {
  await page.goto(
    `file:${path.join(__dirname, "/fixtures/HTML/readonly1.html")}`,
    { waitUntil: ["load", "domcontentloaded", "networkidle0"] }
  • Assert on initial page state

  • Invoke UI actions to trigger behavior

  • assert on final state

Building docs locally#

Thebe uses Sphinx and JupyterBook for building documentation. Thebe documentation is located in the /docs directory. You will need the development environment setup, see the above Set up a development environment to learn more. You will also need Python installed, and can install the requirements for the documentation using:

cd docs/
pip install -r doc-requirements.txt

Once you are in the documentation folder:

make html

This will also trigger a build of the library and copy this into the docs/_static/lib folder for inclusion in the local docs build. To update this local build at any time run:

make js

Finally, run the following to view the built documentation locally:

make show

Additionally, you can run:

make js-dev

at any time to produce for a development build of the library. Development builds enable useful names for modules and remove production optimizations, which can be helpful when debugging.

Releasing Thebe#

To release thebe, follow the EBP guidelines to make sure the repo is ready for release.

Once prepared, bump the version with:

  1. Use yarn to update the thebe version in the package.json file and to create a git tag for the version using yarn version --new-version NEW_VERSION, e.g. yarn version --new-version 0.5.1

  2. Push the tag to github: git push --follow-tags

  3. Create a release for the new tag on github at; this will trigger a github action that uploads the latest version to

Thebe architecture#

Thebe consumes three principal APIs:

  1. jQuery for manipulating elements on the page

  2. JupyterLab for talking to a running Jupyter server to execute code and display outputs

  3. BinderHub for requesting kernels from a BinderHub instance, such as

Manipulating the page#

The first thing Thebe does is find elements on the page that should be made executable. It does this with jQuery, finding (by default) elements that look like <div data-executable="true">..., with a query such as the $("[data-executable]) (this is the default, but can be customized). Once it has found these elements, Cell objects are created (more on Cells in the JupyterLab API), which then replace the elements that were found.

JupyterLab APIs#

The main thing Thebe does is execute code and display output. This is done with JupyterLab APIs. A Cell is an element wrapping a code input area and associated OutputArea for displaying the outputs that result from execution.

Main APIs used:

  • OutputArea for rendering outputs on the page

  • Session for starting kernels

  • Kernel for sending/receiving messages to/from a connected kernel

  • WidgetManager for working with interactive widgets


Configuration is handled by adding a script tag with type=”text/x-thebe-config”. This should specify a javascript object.

More information in the README (TODO: move it here?)

<script type="text/x-thebe-config">
    binderOptions: {
      repo: "minrk/ligo-binder",
      ref: "master",