Is there an HTML/CSS/JS editor that immediately shows changes? [closed]

Question

I just saw Bret Victors Keynote called "Inventing on Principle". At around 3:34 Minutes he uses a code editor that - after a change he makes - immediately shows consequences of it. As he types there are instant results.

This is the video I am talking about: http://vimeo.com/36579366

Another example is this real-time online html editor.

Can you tell me which offline editor I could use to work on my web projects (HTML/CSS/JS) this way? Preferably it can be used on OS X. Thanks!

Answer 1

Brackets looks nice, but still on development.

Answer 2

I don't know if there are any free ones, but TextMate has a live preview window. Just don't download the version 2 beta — I don't think it's been implemented there yet. You can also check out Coda and BBEdit.