amp-bind: TODO list use case

@sebastianbenz suggested amp-bind support a use case like ToDoMVC. One way to accomplish this is to allow amp-mustache to template using amp-bind state.

This would be a cool addition, though I wonder if allowing Bind to add/remove DOM elements is too powerful. @ericlindley-g mentions that this is an app-like use case that hasn’t been prioritized yet.

/cc @cramforce

[middle-way-approach]

I implemented a todo app with just amp-bind to show that it is possible. The only caveat is that the max number of todos is determined by the html structure and can not be dynamically increased. See yourself

[src-code]

I’d love to see this happen, especially for the commenting use case. Seems like it’d be really powerful to be able to update a small piece of state after a form submission, and then use that local state to re-render the template without requiring a re-fetch of the whole data set.