README.md

JupyterLab Extensions by Examples

1. Goal
2. Develop by Examples
   1. Commands
   2. Command Palette
   3. Main Widget Content Header
   4. Context Menu
   5. Custom Log Console
   6. Datagrid
   7. Hello World
   8. Kernel Messaging
   9. Kernel Output
   10. Launcher
   11. Log Messages
   12. Main Menu
   13. React Widget
   14. Server Hello World
   15. Settings
   16. Signals
   17. State
   18. Toolbar Item
   19. Widgets
3. Prerequisites
4. Develop and Use the Examples
5. Test the Examples
6. Install a Published Extension
7. About JupyterLab
8. Credits
9. Community Guidelines and Code of Conduct

TL;DR

The goal of this repository is to show how to develop extensions for JupyterLab, presented as short tutorial series.

To get started:

# clone the repository
git clone https://github.com/jupyterlab/extension-examples.git jupyterlab-extension-examples

# go to the extension examples folder
cd jupyterlab-extension-examples

# create a new environment
conda env create

# activate the environment
conda activate jupyterlab-extension-examples

# go to the hello world example
cd hello-world

# install the extension in editable mode
python -m pip install -e .

# install your development version of the extension with JupyterLab
jupyter labextension develop . --overwrite

# build the TypeScript source after making changes
jlpm run build

# start JupyterLab
jupyter lab

The examples currently target JupyterLab 3.1 or later.

If you would like to use the examples with JupyterLab 2.x, check out the 2.x branch.

If you would like to use the examples with JupyterLab 1.x, check out the 1.x branch.

Note that the 1.x and 2.x branches are not updated anymore.

Develop by Examples

You may find it easier to learn how to create extensions by examples, instead of going through the documentation.

Start with the Hello World and then jump to the topic you are interested in.

• Commands
• Command Palette
• Completer
• Main Widget Content Header
• Context Menu
• Custom Log Console
• Datagrid
• Documents
• Hello World
• Kernel Messaging
• Kernel Output
• Launcher
• Log Messages
• Main Menu
• React Widget
• Server Hello World
• Settings
• Signals
• State
• Toolbar item
• Widgets

You can expect from each example:

• An explanation of its functionality.
• An image or screencast showing its usage.
• The list of used JupyterLab API and Extension Points.
• Explanations of the internal working, illustrated with code snippets.

We have structured the examples based on the extension points. Browse the previews below or skip them and jump directly to the sections for developers.

You are welcome to open any issue or pull request.

Commands

Extend the main app with a Command.

Command Palette

Register commands in the Command Palette.

Completer

Customize tab autocomplete data sources.

Main Widget Content Header

Put widgets at the top of a main JupyterLab area widget.

Context Menu

Add a new button to an existent context menu.

Custom Log Console

Create a new log console.

Datagrid

Display a Datagrid as a Lumino Widget.

Documents

Create new documents and make them collaborative.

Hello World

Set up the development environment and print to the console.

Kernel Messaging

Interact with a kernel from an extension.

Kernel Output

Render kernel messages in an OuputArea.

Launcher

Start your extension from the Launcher.

Log Messages

Send a log message to the log console.

Main Menu

Add a Menu to the main app.

React Widget

Create a React.js Widget in JupyterLab.

Server Hello World

Create a minimal extension with backend (i.e. server) and frontend parts.

Settings

Create and use new Settings for your extension.

Signals

Use Signals to allow Widgets communicate with each others.

State

Use State persistence in an extension.

Toolbar Item

Add a new button to the notebook toolbar.

Widgets

Add a new Widget element to the main window.

Prerequisites

Writing an extension requires basic knowledge of JavaScript, Typescript and potentially Python.

Don't be scared of Typescript, even if you never coded in TypeScript before you touch JupyterLab you may find it easier to understand than pure JavaScript if you have a basic understanding of object oriented programming and types.

These examples are developed and tested on top of JupyterLab. You can create a conda environment to get started after cloning this repository.

conda env create && \
  conda activate jupyterlab-extension-examples

The previous command will use the environment.yaml file as requirements for the environment.

Develop and Use the Examples

Build and Install all Examples at once

jlpm
jlpm build-ext
jlpm install-py
jlpm install-ext
jupyter lab

To rebuild all the extensions:

jlpm build-ext

To clean the lib folders:

jlpm clean-ext

Build and Install one Example

Go to the example directory you want to install, e.g. cd ./hello-world, and run the following commands:

pip install -e .
jupyter labextension develop . --overwrite

Rebuild the extension:

jlpm run build

You can now start JupyterLab and check if your extension is working fine:

jupyter lab

Change the Sources

If you want to develop and iterate on the code, you will need to open 2 terminals.

In terminal 1, go to the extension folder and run the following:

jlpm watch

Then in terminal 2, start JupyterLab with the watch flag:

jupyter lab --watch

From there, you can change your extension source code, it will be recompiled, and you can refresh your browser to see your changes.

We are using embedme to embed code snippets into the markdown READMEs. If you make changes to the source code, ensure you update the README and run jlpm embedme from the root of the repository to regenerate the READMEs.

Test the Examples

The examples are automatically tested for:

• Homogeneous configuration:
  Configuration files are compared to the reference ones of the hello-world example
• TypeScript code lint
• Installation in JupyterLab:
  The installation is checked by listing the installed extension and running JupyterLab with the helper python -m jupyterlab.browser_check
• Integration test:
  Those tests are emulating user action in JupyterLab to check the extension is behaving as expected.
  The tests are defined in the ui-tests subfolder within each example. This is possible thanks to a tool called playwright.

Install a Published Extension

Once your extension is published on pypi.org (outside of this scope), you can install it with the following command:

pip install <published_extension>

About JupyterLab

JupyterLab can be used as a platform to combine existing data-science components into a new powerful application that can be deployed remotely to many users. Some of the higher level components that can be used are text editors, terminals, notebooks, interactive widgets, filebrowser, renderers for different file formats that provide access to an enormous ecosystem of libraries from different languages.

Complementary to these examples, you can rely on the official JupyterLab documentation.

• Extension Developer Guide
• Common Extension Points
• Astronomy Picture of the Day JupyterLab Extension

Credits

We would like to thank MMesch for initiating this work, as well as everyone else who contributed!

Community Guidelines and Code of Conduct

This examples repository is a Jupyter project and follows the Jupyter Community Guides and Code of Conduct.