Hasn't the 1 year in Java made you a better Javascript programmer? I assume you haven't just been learning language syntax, but have been developing patterns that are deployable across languages. Of course, you would have been a better Java programmer if you'd spent 4 years with Java, but don't underestimate the value of the generalist approach you've taken.
It definitely has; I think programming in any language makes me a better programmer in any other language.
However, my concern is applying for jobs relevant to my level of software engineering experience, but requiring X amount of experience in Y. In a situation where I believe my ability is equivalent in Y, is the solution to exaggerate a little on my time spent on Y? Maybe it's not even a big deal in the first place :D
