As a test developer, I love making tools, and I like to share my tools. It is always great to hear about how cool your tools are or how much their lives have been made easier.
In the past it wasn’t easy to distribute my tools, one reason is that not everyone has Python on their machine. It is totally different with JS. If you have a browser, you can run my code. It can be remote on a server, it can also be in a local folder.
It is also super simple to have nice-looking UI in JS, because HTML/CSS is much easier to tweak. I am not saying I don’t like command-line interface, just sometimes it is more intuitive to have a cool graph. There are also many ready framework you can grab from the internet, including one of my favorite Twitter Bootstrap. Not to mention countless JS plugins to show off/manipulate your data.
To get work done quick, you might also need a good JS framework. There are never lack of framework options in JS world. And that is also a problem. Personally, I prefer AngularJS. The learning curve is not steep (at least in the beginning:)), and the built-in features are enough to put my ideas into applications. Also the code structure is very neat, which I like very much.