That depends. CSS prototyping is usually easier in Firefox. For example grid editing, flexbox, shape path editing.

I mostly switch to Chrome when debugging PWA. Other then that Firefox gives me better UX.

class A defines a let variable. It's how the standard define it.

You can replace A with: A = class {...}

This works with any browser.

BTW. In Firefox there is a multi line editor. With code completion. I actually find more convenient to test large code fragments in fox because of that.

Good tip, thanks, but it means that code written like

  class A {}

has a huge difference from code written like

  A = class {}

In classical JavaScript consider how small the difference is between

  function foo () {}

and

  foo = function () {}

Function hoisting only works for the "function foo(){}" form so there's a difference but they intuitively work essentially the same and either form works well when experimenting in the console. If enough rules like "class A {} is very different from A = class {}" are piled onto JavaScript it's going to become like C++, a language so complex that people would rather learn a simpler language so they can focus on the complexities of their actual problem space rather than the complexities of their language. A new language called Zig is now trending upward because a growing number of programmers would rather have a language they can 100% understand after a reasonable time investment rather than a language like C++ where even after a 20 year career with it and implementing portions of a compiler for it you still get painfully surprised by some obscure rule interaction you never dreamed to imagine possible.

The project is interesting... But I don't understand your point about JSON vs JS.

1. You can store JS anywhere (all DBMS support text).

2. You can send it over the Internet... Like everything else nowadays.

3. You can compose JS easily.

4. You can validate JS using linters.

5. etc.

Besides... Aren't you only disguising functions in strings? You can eval strings anyway.

No, for OS you decide which compilator to choose. As is with browsers. There are several languages (e.g. TypeScript, CoffeeScript, Dart) which can be compiled to JS.

That is not what I personally like (the processes of compilation and deployment I mean), but if you develop for OS then you have to compile before you run... In most OS.