This one line was like 90% of the original implementation of Writely (the startup that became Google Docs; source: I was one of the founders).
The other 90% was all the backend code we had to write to properly synchronize edits across different browsers, each with their own bizarre suite of bugs in their contenteditable implementations :-)
The other 90% was all the backend code we had to write to properly synchronize edits across different browsers, each with their own bizarre suite of bugs in their contenteditable implementations :-)