1) If you are going to suggest such a massive scope of changes, offer to help instead of just dumping a list out there.
2) Check to see if the poster on HN is actually the author of the article. Doesn't look like it in this case, so you may be talking into a vacuum.
3) I love that timeline widget. But it is one of the most un-intuitive and complicated things I have ever seen. I recommend re-coding its functions into a simpler library vs. adding even more complexity to timeline.
4) Dependencies can get evil. Your suggestions add quite a lot of complexity into footprint of plugin. I fear that the end result might look good to a coder, but be a bit of a nightmare to actually use in a production environment.
2) Good point. Can't argue that.
3) Maybe. Maybe not. It would need to be investigated further.
4) I made those suggestions based on code I've got in production. Other than Timeline, I suggested two libraries, both of which would remove a lot of code duplication in the Gantt plugin.
Some suggestions:
#1. Switch to CoffeeScript. It will cut the size of the code down considerably and given that it is such a massive file, it would really help readability.
#2. Don't embed so much html into the code. That'll also cut down code and make things easier to read. I suggest something like Handlebars to render things. Yes, another dependency, but a good one.
#3. Do you really need the 'please wait' to render things? It is somewhat jarring when clicking around quickly. If anything, just switch the thing you clicked on into a spinner or display a small spinner somewhere.
#4. A lot of the date math that is going on could probably be done more easily by using momentjs. Again, another dependency, but will save you code in the long run.
#5. Grey out buttons which cannot be clicked further? Like the + and - buttons.
#6. Maybe consider integrating or building on top of the Timeline project? http://www.simile-widgets.org/timeline/
Cheers.