The trick is practice. The more you use the language and APIs the more you'll remember. If you don't remember then a search engine is your friend. Libraries are

The trick is practice. The more you use the language and APIs the more you'll remember. If you don't remember then a search engine is your friend. Libraries are so big these days that you can't be blamed for not remembering something. When I'm coding in C# I'll just google the API I'm using, which typically leads me to MSDN. When I'm coding Elixir I just head to Hexdocs.pm because the documentation is just fantastic.