How can I add a table of contents to a Jupyter / JupyterLab notebook?

Question

The documentation at http://ipython.org/ipython-doc/stable/interactive/notebook.html says

You can provide a conceptual structure for your computationa

Answer 1

I recently created a small extension to Jupyter named jupyter-navbar. It searches for headers written in markdown cells, and displays links to them in the sidebar in a hierarchical fashion. The sidebar is resizable and collapsible. See screenshot below.

It is easy to install, and takes advantage of the 'custom' JS and CSS codes that get executed whenever a notebook is opened, so you don't need to manually run it.