Ask HN: Online Editor for Quick Prototyping

I'm looking for a js editor that can edit both regular text and have support for code to some extent.

something like this but for more than one input methods: http://www.openstenoproject.org/demo/

I want to expose some basic functionality to the keyboards so that they can perform the magic on a meta level as well. Think command mode in VIM.

Any suggestions?

I'd be very grateful for any good pointers as I rather not spend a month digging through the code of an editor.