Smalltalk on the web.
Ranked in these QuestionsQuestion Ranking
Pro Includes an IDE
Amber includes an integrated development environment with a class browser, workspace, transcript, object inspector and debugger.
Pro Smalltalk is a simple, elegant, and powerful language
Pro One-to-one JS equivalent
Con Very few learning resources
There are very little learning resources for Amber outside the official documentation. Which may not be enough for beginners, especially people that don't have much experience in programming.