Here's how out-of-the-loop I am: I'd don't know the command line method for invoking the JS runtime on my computer! What it is? I regularly image my laptop, so I'd like to know what the system JS command line is. (I use Linux & macOS.)
The CLI runtime that 99% of people use is Node.js, available via the same package manager where you'd get Python 3.
Its dependency management story is not great, but in general better than the horrible mess on the Python side.
On macOS there's a system runtime called JavaScriptCore.framework. It's actually a very good and useful engine. If you're writing native code, you could link to that. But of course it doesn't provide any of the Node.js API, just the JS standard library which is tiny. So the most typical use case would be to embed a JS API into your application.
