My objection to the idea that JS will so easily replace Python is that if you apply the same degree of analysis to JS that is causing you to reject Python, JS fares
far worse. At least Python
addresses the encoding issue, JS strings are far stupider, more dangerous, and require you to do a lot more of the paperwork if you can't assume an external environment that takes care of it for you (the browser, in this case). The next generation of JS fares somewhat better, if it is implemented according to the spec (and there quite a gulf betwixt a spec and an implementation), but when will you start being able to use that?
Try implementing even a medium-sized project in both Python and JS and tell me JS is a serious replacement, let alone for the large ones.