Deserializing sub-widgets with ipywidgets (originally from https://stackoverflow.com/questions/56477875/child-widget-creation-in-ipywidgets-produces-an-error-using-viewlist-and-create/56537296#56537296)

widget-deserialization.ipynb

Will that "modern" version run in most browsers?

No -- to get sufficient browser support, it needs to be transpiled to 'old' [*] JavaScript using a tool like Babel or typescript, and bundled using something like webpack.

A good heuristic is:

• if you have a very simple frontend, then keeping it in 'old' JS is probably safest. If you have no experience of Babel and webpack, I'd expect it to take you a day or two just to get something working (based on my personal experience as a Python developer who had to learn JS that way).
• if you are going to develop a rich frontend library, then the investment is worth it. 'New' transpiled JS is just nicer to write.

[*] here, 'old' JavaScript means JavaScript that can be executed by all the browsers you want to support. It's useful to note that this isn't well-defined: the latest version of Chrome will accept lots of modern syntax, while IE 11 won't. For instance, pasting the following in my chrome console works just fine:

class Hello {
    static prop = {
        a: 22
    }
}

Hello.prop
# {a: 22}

I might try submitting a pull request to update the docs with this small tidbit

Yes! That would be great! Jupyter widgets are purely maintained by the community -- there is no commercial company behind them, so we're very heavily reliant on contributions like these.