I found Becoming Steve Jobs by Schlender & Tetzeli to be a much more informative read than Isaacson's official biography, particularly on the intersection of Jobs/Next/Pixar/Apple.
Check out http://quilljs.com -- it's a cross browser rich text editor that does provide such an api.
Granted, it doesn't yet have all the functionality of a complete word processor, but it's early days and its module system provides good extensibility. Part of what's exciting to me about it is that it's also a good chance to rethink what a word processor should provide in the context of the web, instead of simply porting what made sense when the target was printing a document to paper.
> I couldn't figure out how to remove a URL from a selection of text.
If you highlight the text, and click the link hyperlink icon in the toolbar, the URL will be removed. The link overlay UI doesn't support that though; we'll add a "remove" action in addition to "change".
It represents "doomed" text that eventually gets removed from the final draft. You can toggle it by clicking "doomed" in the upper right. See http://paulgraham.com/stypi.html