Apart from being used by everybody, do they have any other reason for using JS? In general, I'm curious why JS is picking up so much for backend development? Is it just that people like using one language?
This may not be the venue for me to surface this, but I've been trying to wrap my head around the MEAN stack for about a month now, and it doesn't really even register to me as the same language. I'm using Angular on the front end and ExpressJS plus Mongoose (MongoDB) on the back end, so yeah, it's all technically Javascript, but the real learning curve was in working out how to get these big frameworks to do what I wanted. I sincerely believe that if I was using an Angular frontend to call a Django REST service, I'd have had the exact same amount of trouble grokking what was going on (async calls being the obvious exception).
Am I thinking about this the wrong way?
You only spend some time grokking the basic syntax of the language.
Most of the time is spent getting the frameworks working and talking to one another. The frameworks having the same underlying language does not gives you much advantage.
The reason I reach for Node on a project is to handle my websockets. I use Django REST Framework + Ember as my main tools (super fast to build with) but, based on my testing, Python can't hold a candle to Node when working with thousands of websockets. It works great for what it was designed for.
I'm building a side project right now and I'm using Django running inside Tornado (it's pretty simple to setup, really) so I can both have my cake and eat it (easy APIs, and a layer I can use to maintain websockets.) I wonder if the performance would be comparable to Node?
Although Ember really feels like idiomatic Javascript to me and they try hard to adhere to new web standards (e.g. web components, ES6 modules) it is also very opinionated about what should go where and how.