Observable notebooks exist. The issue for JS replacing Jupyter is that Python already has a large number of scientific libraries where the performant ones are based on wrapping C++ or Fortran code. You can handle more data and processing on the server. Also, because Jupyter gives you shell access and other languages like R can make use of it.

Language-wise, the other issue JS has is that it lacks operator overloading, which makes array handling a lot nicer. Python has magic methods for doing that. Julia, R and Matlab have that built into their languages. Julia also has it's own version of reactive notebooks similar to Observable.

And then you have a lot of scientists who already know and use Python, R or Julia. I can't really imagine a statistician who's well versed in R finding much value in JS. Javascript just isn't made for complex statistics the way R is.

JS now feels like Java back at the turn of the millennium, when people were thinking Java could just be used for everything, and it sort of was. Or any language could run on the JVM (the web has largely replaced that idea). But there's a reason for the various different programming languages. Some are just better at doing certain things. And JS is not a scientific computing language.

Check out Starboard (https://starboard.gg, I'm the creator). I think it's exactly what you're looking for (you can use plain dom, html, css, javascript, python).

Checkout https://github.com/jupyterlite/jupyterlite, WASM'd Jupyter in the browser with Pyodide

Nice, my instinct reading the above was: The (future) target of this could be WASM instead of JS.

It's a very promising technology IMO. Not necessarily because it is faster (which is only 0.3x-2x according to my findings) but because it is a nice, simple compilation target.

Only you know your data volumes but for the scenarios in which I've reached for Jupyter they've often involved very large amounts of data and calculating on the server is what I wanted and needed.

Agreed that for some things, it would be great to be able to explicitly offload to the browser.

Yes, my dataset is tiny. I mainly use the JS notebook to analyze my selftracking log [1] which is about 10k lines of data at the moment.

I have not yet tried to load a lot of data into it. Would be interesting to see when the load time starts to outweight the benefits of instant calculations. Maybe at something like 10 million datasets? Hard to say.

1: https://www.gibney.org/a_syntax_for_self-tracking

Have you seen https://nomie.app? You can use a CouchDB backend to store the logs as semi-structured data.

My usecase for jupyter notebooks often is to use the server to calculate stuff, though. I rent some beefy 16 cpu, 128gb ram, tesla p100 machine so that my laptop won't melt.

On the javascript side there is https://observablehq.com

You can, with pyodine: https://github.com/pyodide/pyodide

Here is an example instance: https://notebook.basthon.fr/

The thing is, creating a whole stack in pure JS would be very hard, since the current scientific stacks uses a lot of fortran, assembly and C with python to bind them all. Or julia. It's millions of man hours we are talking about.

So compiling Python into WASM is probably the best deal for such an app.

For the regular web, it would be a deal breaker: you don't want to load 15 mo of runtime before being able to interact with a web page. But for such a scientific app, it's not a problem. Besides, were you to write it entirely in JS, the size would be huge as well.

I'm working on a version of this: https://instadeq.com/

I believe Google Colab provides what you described.