I really like the idea behind Kite – using WebKit's own protocol for remote debugging. No need for a proxy socket server or a bookmarklet to connect to a web-page (that's how swank-js operates).
The project's readme states that Kite...
"enables ... live-editing Web pages".
However, while kite-scratch works fine, I can't eval defuns or whole buffer while not in the kite scratch.
Is it possible to eval JavaScript with Kite in any buffer other than kite-scratch?
It looks like kite-scratch-mode is a mode derived from javascript-mode, so you might just be able to use M-x kite-scratch-mode to enable the kite-scratch bindings in your javascript file.
I'm sure it's not designed for that, though, and so you might consider asking the author for a minor mode which supplies bindings similar to those of swank-js or js-comint.