It wouldn't be my first choice either, but modern JavaScript isn't backwards-compatible, it is at least possible to write reliable and robust code if you take some care and know what options to enable, and it's mostly consistent across platforms. Last month, I spent a week trying to handle all of the possible error conditions in an overgrown bash script. It was immeasurably worse.

Python is the more direct substitute, though: it's built-in to almost every platform, and the Python 3 stagnation has even given us a consistent version: 2.7.