With Javascript being the mess that it is I doubt it would be a good starting language, it has too much idiosyncrasies. Most of the post seemed to be excusing Javascript's faults and trying to convince me that I have a problem with said faults because I've been exposed to "better" programming languages. No shit.
To be fair, Javascript is the easiest language to teach through a website, but that's it. The goal shouldn't be to make the teacher's life easy rather then providing the right tools for the student.
Don't underestimate the power of the web though. For a new student/user, there's a big difference between step 1 being "click this link" rather than "follow this intimidating installation process".
Javascript is not ideal, but it's quite good, and it's there, already running in a sandbox on the student's machine.
To be fair, Javascript is the easiest language to teach through a website, but that's it. The goal shouldn't be to make the teacher's life easy rather then providing the right tools for the student.