learn how a relational database works (this is always useful)
learn how HTTP works in general
learn how to debug code in one language (it's pretty much the same in others, you can recycle most of the knowledge)
be familiar with the command line
know how to find code (either using your IDE or grep on the command line)
knowing the basics of regular expressions will get you far (also to find code in the previous point)
know how to find solutions using a search engine
know how to operate git (I would say any source control but git is the de facto standard so you might as well start with that)
ask questions, especially if you think they're not worth being asked
learn how timezones work (not kidding, lots of devs are still fuzzy on these)
learn how unicode and utf-8 work (same reason for timezones)
have a general idea of how caching (CPU, in memory, disk, HTTP) works as a concept
notice that other than git I didn't specify any particular tool, this is because it's stuff you will bump into no matter which languages or tools you'll end up using.
Hi Julia!
in no particular order:
notice that other than git I didn't specify any particular tool, this is because it's stuff you will bump into no matter which languages or tools you'll end up using.
Worthy of a boost:
12 Things Every Junior Developer Should Learn
Ben Halpern
Ahah! Thanks Ben!