Reasons to like js:

1) There are very fast implementations in production, as well as an arms race between some of the world's most powerful titans of software development to outdo each other at js vm performance.

2) It is a thin abstraction over the Reactor Pattern, which is very useful for certain kinds of event-based applications.

3) Very lively and robust package ecosystems in npm (node) and jQuery (web). Virtually all packages are async by default.