Reddit reviews Learning Dart

Honestly, http://dartlang.org has all you need to get started. Dart is essentially just java, but optimized for the client-side web and compiling to javascript, so it doesn't depend on classes, supports more functional methods, and has nice/easy to use systems for asynchronous functions and concurrency. You can compile it to javascript and use web apis, but you can also use it from the command line and use the file/networking/os apis.

A book that helped me was Learning Dart by Dzenan Ridjanovic.