Where is a docs for Jupyter front-end extensions JavaScript API? - jupyter-notebook

Question

I've read the docs about writing the Jupyter front-end extensions, and learn the examples, and now can build the simple extension by myself.
But - where is a complete docs for Jupyter extensions JavaScript API? How to find the JavaScript API for notebook properties and methods?

Answer 1

This answer is outdated. Also see answer below.
This might not be the answer you hoped for. However, it might help some readers being new to JavaScript development.
I also was looking for documentation on the Jupyter client API and could not find official docs.
The JavaScript source code can be found on the GitHub repository, for example:
https://github.com/jupyter/notebook/blob/859ae0ac60456c0e38b44f06852b8a24f8a1cfb0/notebook/static/notebook/js/notebook.js
https://github.com/jupyter/notebook/blob/4.2.2/notebook/static/services/kernels/kernel.js
What also helped was to
A. Use Google Chrome development tools, set a break point in the extension and type
Jupyter
in the console. Then you get a browsable tree structure that can be used to inspect the Jupyter object. That tree structure does not seem to contain methods.
B. Log all the properties of an object, including the methods. If you want to know about the methods of the notebook use for example
for(var property in Jupyter.notebook){ console.log(property)}
C. When typing in the console there is code completion. For example you might want to type
Jupyter.notebook.
and see the suggestions on how to complete the command:
Also see
How to inspect Javascript Objects
How to display all methods of an object?
https://www.codeproject.com/Articles/24549/How-to-Inspect-a-JavaScript-Object
Chrome Developer Tools console - inspect JavaScript object
Browsable tree structure in dev tools console:
How to list properties including methods:
...

Answer 2

For newcomers it might be confusing that there are several projects with similar names for historical reasons:
a) Jupyter
https://github.com/jupyter
b) JupyterLab
https://github.com/jupyterlab/
The webpage https://jupyter.org/ references the newer b). However, the sub projects of a) do not include deprecation warnings.
=> If you find some documentation via search engine, you have to be careful if its related to a) or b).
Current documentation for JupyterLab extensions can be found here:
General info:
https://jupyterlab.readthedocs.io/en/3.2.x/user/extensions.html
Javascript API doc:
https://jupyterlab.readthedocs.io/en/stable/api/modules.html
Examples:
https://github.com/jupyterlab/extension-examples
Discussion forum:
https://discourse.jupyter.org/c/jupyterlab/extensions/
Related:
https://www.quora.com/What-is-the-difference-between-JupyterLab-and-Jupyter-Notebook-Is-there-a-use-case-for-one-over-the-other?share=1
https://github.com/jupyterlab/jupyterlab-plugin-playground

Answer 3

Apparently, there are is no front-end API documentation, as there is an open GitHub issue that even references your SO question. Maybe a few +1s on the issue might change this, although I suspect that the answer (if any) will point to JupyterLab, which has a defined front-end API but has no common technical base with Jupyter Notebook front-end extensions.