I think the responder means that duplicate code is usually easy to refactor into single methods. Typically I see copy pasted code that is changed just a little bit. However much of a duplicated function can be broken into smaller functions and the redundant code removed in favor of calling into the functions. Often what is left then becomes easier to reason about and refactor accordingly. I love the PRs that I make which delete more code than I add but still manage to add functionality. It doesn’t happen often but it’s fun when it does.

If your primary exposure to programming is only typescript or JavaScript maybe you shouldn’t be jumping straight into something like rust. JS is a high level language and rust is aimed at the lower levels where things can’t be as automatic. There are many languages out there like C#, Kotlin and Swift that will help you get used to the idea of strong types and immutability.

The only things JSON has over xml is that it’s easier to write a parser for it and the format is less verbose and less complicated. There are extensions to JSON that can add features that xml has and the JSON spec doesn’t have. Overall the xml spec is bigger and has more features but that also makes it overkill for many of the cases that it would be used in.

There is a school of thought that break and continue are just goto in disguise. It helps that these two are more limited in scope than goto and can be considered less evil. If you read the book Clean Code by Robert Martin (it should be required reading for all developers), you’ll see that he doesn’t like functions to be very long. I think his rule is no more than 4 lines. I try to keep mine around 10 or less with a hard stop at 20 unless it can’t be avoided because I’m switching over a large enum or something. If you put your loops into functions then you can just use return instead of break.

I did have a discussion with a teacher once about my use of early returns. This was when I had returned to school after many years as a professional programmer. I pointed out that my code has far less indentation than theirs and was simpler because of it and that it is common in the world outside of education. I got all of my points back he has deducted.

You’re going to hear some good and bad advice from your teachers. Once you have a job check out what the good developers are doing and just follow them.

I wish I could say that Google is better at that. It’s basically the same story but with even less humans to talk to when you’re flagged for doing something wrong or in the case of Google your former college roommate whom you haven’t seen in 10 years did something wrong. It’s the price all mobile devs pay unless they only want to distribute to a small subset of users who have liberated their phones.