Are the language/syntax differences documented somewhere? It's difficult to tell if something is an obscure early stage ecmascript proposal or a language feature specific to observablehq. For example in https://beta.observablehq.com/@mbostock/introduction-to-note...

  import {canvas as flood} with {height} from "@mbostock/randomized-flood-fill"

or how you define generators

  i = {
    let i = 0;
    while (true) {
      yield ++i;
    }
  }

etc

We’re still writing more documentation, but there’s a bit more detail here (and I’ll be posting more soon): https://beta.observablehq.com/@mbostock/introduction-to-code

To summarize, the body of a cell is typically either an expression or a block statement, akin to the body of an arrow function. If a cell starts with name = …, then it has a name and can be referenced by other cells. So, the name = part is specific to Observable, but the expression and block statement is normal JavaScript.

The import declaration is similar to a normal static ES import, but the with clause allows you to inject local definitions into the imported notebook.

I got a little tripped up because I tried to assign a literal object to a name.

e.g.

    name = { foo: 1 } 

doesn't work. I ended up doing:

    name = { return { foo: 1} }

but after your explanation, I guessed that this would also work:

    name = ({ foo: 1})

Yep!

There is mybinder.org to run jupyter notebooks online . For example, https://github.com/norvig/pytudes

There's also some (currently) free cloud version by microsoft available on https://notebooks.azure.com in a preview state, but works great already. (Tested python3 only)