This to me feels really underrated nowadays - at best, you shouldn't always have to reason about your code inside of your head and try to figure out how it'll work in detail, or read API docs for all of the obscure frameworks that you're using.

Test things in real time at first and in the cases where they don't, continue doing so, but with a debugger and stepping through everything bit by bit, or read the docs, or whatever the non-trivial cases will demand.

In my eyes, that's the exact same thing as autocomplete in IDEs - instant feedback, to free you from having to think about yet another mundane level of abstraction or API details, instead letting you solve the actual problems that you're faced with.