What's your definition of "must learn?" Personally, I believe that to study JavaScript is also essentially to study web anthropology—it's incredibly useful for understanding the tech culture of today, regardless of whether you personally program for the web. As a language that started client-side and expanded far beyond that, JS has become uniquely accessible to both sides of the experience graph as it's become more complex and multi-paradigm. Largely owing to its user base containing so many semi-technical professionals, the language has evolved specifically to provide simple APIs for all the most common paradigms. Simultaneously, that is its biggest pitfall, from my perspective as someone who spends a ton of time mentoring newbies: it's so multi-paradigm that it's easy for an unexperienced developer to accidentally code using the worst features of each paradigm simultaneously, instead of the best. On top of all that, the JS open source community is particularly diverse and interesting, what with the incredible versatility of the language. So, yeah, just wanted to call attention to the fact that there's a ton to be learned from JS that doesn't even necessarily have to do with using it to code a thing. Whether that's relevant to your needs is your call. ;)

I think in pure functional logic and store information in an n-dimensional representation of a directed graph, and I love coding languages for their precision. Multipurpose functions, to me, are quite literally poetry. I love building complex idioms using tiny bits of logic as my vocabulary. I love writing scalable, maintainable code that reflects the perfect order of my inner logic. I love diving into a bit of code and feeling like I'm discovering something amazing and perfect—that rush of insight when I "level up" and suddenly can use a new skill to its fullest potential. It's so creative; programming feels exactly the same to me as writing music, cooking a dish from scratch, playing an open-ended game with infinite possibilities.

I'd refactor the source code for the human brain from an object-oriented paradigm to a functional one. I mean, as long as we're dreaming and all.

As a huge extrovert who's super into networking, my biggest reason for using Twitter is the ability to directly engage with people in a manner you usually don't find outside private communities. I just treat it like a big cocktail party: Talk to everyone, jump into random conversations, and don't take it personally if nobody really pays attention to me sometimes.

Exactly! Also, transferable skills. If you take every library, technique, and framework out of context like it's some kind of black box, you're gonna get confused...but if you look at the foundational concepts they're built on, you're gonna learn a ton that'll apply to all kinds of things in the future.

I don't know what a developer should do, but here's my process: How do you implement X in lang Y? - Work with the interviewer as if you're pair programming. Even if I totally have no idea about something, I usually say I "don't remember" things about it and come up with some educated guesses about it based on the context they're giving me. Then I start from those assumptions in order to define "X" in great detail, confirming each piece with the interviewer as I go. If I do it right, the process of discovery/learning from my interviewer looks identical to when I already know the thing, because either way, I am taking care to confirm all my assumptions. I also always make sure they provide at least a sample input/output so that I have an accurate representation of THEIR assumptions about its behavior. This is a place where newbies will often out-perform mid-level developers, because they're less inclined to make assumptions in an attempt to show off technical skills. Do you know technology X? - This is an opportunity to have a conversation with the interviewer about what X is and what transferable skills you have from working with other, similar things. Talk about the features of X and how they compare to other offerings out there. Highlight anything that's similar, especially if you can show a deep understanding of the similarities between different technologies. For example, I've been known to talk about the transferability of React/RoR skills in someone with strong CS/OOP basics. This is a great opportunity to learn more about technology X in general, too! By talking to your interviewer, you'll get a better picture of why they're an enthusiast about the technologies their company is using (or why they're not but it's still "good enough," which is SUPER useful information—nuanced opinions are usually the most informative). TBQH, by FAR the most successful approach I've taken to interviews is to treat them as an opportunity to learn, and fully lean into the joy of learning.