I've only written a small amount of dart so far, but speaking as as a cranky C++ developer with not much recent experience with web development, having a thicker standard library is very useful. Specifically the platform has grown so much over the years it's hard as a newcomer to discover the well lit path. With dart:html for example, it's much more straightforward - they have done a lot of work simplifying the very broad set of DOM APIs. I understand there are various JS libraries that provide this, but as a newbie which one do I pick?