I forgot to ask. Does particle physicists that work using Python also use JupyterNotebook/JupyterLab?
Not to my knowledge.
I'm wondering if Javascript communities can also take parts someday by providing custom widgets/extensions for visualization or mini-dashboard.
We need more tools for doing actual calculations than visualizing things. From there, I am not too sure about what could javascript brings. This being said, this cold be useful for outreach.