I'm not sure if it's "almost done". I bought the MEAP (early access) a long time ago, and for months nothing happened at all. Then a second author came on board to get things moving.

A few days ago I got an update from Manning:

    "What's new?
    Chapter 2, "Testing and Debugging" has been added.
    Chapter 3, "Functions are fundamental" has been revised.

    What's next?
    Our next update will be coming quickly, with revised versions of Chapter 4 on closures and Chapter 5 on object-orientation with prototypes.

I haven't bothered yet to actually look at the PDF, it sounds like it's still in a rather early stage.