Just be careful with your long term investment in jQuery - it has a dangerous habit of discouraging acquisition of “proper” JavaScript skills (much in the same way many JS frameworks discourage acquisition of “proper” web application (solution) design skills 
).
You Might Not Need jQuery
You Don’t Need jQuery (anymore)
5 Reasons Why You Need To Learn To Use JavaScript Before jQuery | kaidez
So you know jQuery. Now what? | Remy Sharp
jQuery considered harmful | Lea Verou
I don’t buy this. People that hate on jQuery forget that just a few years ago it was the cure to the madness that were different browser standards and APIs. It became a victim of its own success as browsers started to converge[1]. Obviously, you should know a bit of JS before using it (though not too much if you just want a basic site), but it’s definitely worth it and it may save Red a lot of trouble.
jQuery doesn’t discourage proper JS skills any more than Phoenix discourages OTP and Elixir knowledge or Rails does with Ruby knowledge. It’s not jQuery’s fault that people too lazy to learn JS call themselves JS devs when all they know is jQuery 
That said, your last link is great and there are smaller alternatives like Zepto and fetch (for Ajax) that do the job well. I just don’t like to see jQuery being bullied for the wrong reasons!
[1] Still useful: John Resig on X: "Just a reminder that jQuery 2.x still fixes 88 bugs in modern browsers to give you a consistent dev experience: https://t.co/SBwTFg1IqM" / X
I’m partial to React, but if you’re looking for more of a framework, I suggest Ember. The performance improvements in their somewhat-recent 2.0 release have put it back on the map.
If a person is looking to learn a framework to use in commercial projects Elm is not exactly at the top of the list 
Hey. NodeJS developer here.
Not necessary. Especially a website similar to Hacker News. You can just use plain Elixir/Phoenix (server rendered). This will also helps easier indexing by search engine.
In case you want an easy JS framework/library. I suggest React + MobX. I came from Angular, React/Redux, and I feel React + MobX has a nice balance between those two.
As others have suggested. Keep the brunch for now. It’ll come in handy
There is little demand for elm work, so if a person is looking to learn 1 framework and be able to make a living programming using it Elm is not an ideal candidate.