The focus is on learning. When you start learning, you shouldn't focus too much on "what is best" and "what are other people learning" because you're a beginner.
Experienced programmers can learn a new language in a few weeks, and know enough about the language's idiosyncrasies in a few months to be relatively proficient.
It's the concepts and paradigms that underpin all languages that are important to learn, especially in the beginning.
I disagree. You should very much be focused on that, at least if you care about employment OR about any particular projects. Certain languages really do have advantages - sometimes large ones - in certain domains. If you want to do web work you really don't have a choice about the javascript. If you are interested in working on operating systems or talking to hardware then you will need to learn C.
Javascript and C don't work even remotely similar to one another, just the syntax looks similar. To spend a lot of time on one while you interests lie in the other realm is just silly.
If you only every learn JavaScript, how will you know?
Isn't that an argument for building a toolbox?