It'd be cool to see a version that allowed you to login and vote. Session management and all that entails can be really tricky to implement correctly, and it's a frequently asked question with most frontend frameworks.

I haven't read through each repo's source yet, so take what I'm saying with a grain of salt. Glancing through each repo, only the Angular 2 version has tests. It's pretty easy to write throw away code that works once and you don't have to maintain long-term, so I'd advise caution in adopting patterns from these examples.