It's of course the de-facto language for interactive display in browsers. The use case for dashboards and data visualisation is clear. But it's an awful language for data science and data analysis, compared to Python or R.
So you absolutely can do the data processing step in R or Python and have that output JSON or CSV which is then visualized at the end using JavaScript.
Not a small feature, but I bet it would be possible to use WebAssembly to add support for Markdown blocks that get executed in other languages as well, using Pyodide for Python for example.
This is it, more or less.
It is far, far easier to build an app like this where you want a plethora of users as a web application than a native one, for instance.
For anything JavaScript as a runtime / language is missing, WASM can boost as well. For math and data science, WASM is a natural choice for any missing pieces
I myself like the self-contained aspect of it, since I can publish static files. Also, D3 is the pioneering library for data viz on the web. Especially with maps, which is what I've used it for back in the day. Time to refresh those skills.
I wonder if one could combine this and reactive Python based Jupyter notebook alternative https://docs.marimo.io/guides/wasm.html
Perhaps with web component packaging it should be doable. Web component attributes might allow tying reactive events from one side to the other.