Oh? Could I subjectivly suggest that Javascript would be appropriate for a system with hard real time requirements or formal verification requirements?
Sometimes using a band saw to conduct brain surgery is just completely wrong.
It's pretty clear that COBOL would be a bad choice to write a multiplayer online game, and that JavaScript would be a bad choice for an operating system.
As for the far far more common scenario (the one I had in mind) of choosing whether one of Ruby, Python or Node.js might be better for a certain project, the choice between the three is often going to be fairly subjective. You could solve a lot of problems in all three quite well. Trying to decide which one is objectively the "best" is often a waste of time that could be spent actually solving the problem at hand.
Sometimes using a band saw to conduct brain surgery is just completely wrong.