Hardware Control using Desktop application connected to a web-based application

Hi Everybody, First of all, I'm new to Hashnode and Javascript! So accept my apologies if the questions are a bit general or maybe stupid!

The question that I have is how much flexibility/access you can have with javascript to access hardware on the client's computer. For example, if the user has a Camera, Speaker, or other I/O devices connected to their computer, can one give permission to a website so that website can control his/her devices remotely? Is it possible to use javascript for this?

If it's not remotely, can you have a desktop app written in javascript that can access your hardware?

And more Generally, how do desktop apps connect with their website account? For example, on almost every desktop app you can create/login to an account which will then fetch your information on your account and show it to you. How is this done from programming point of view? Should both of them be in javascript? if you want to have the same functionality both on the website account and desktop application, how do you share code so that you don't need to do everything again for your desktop app?

I'll appreciate your help.