JS is overwhelmingly edited in text editors, see Sublime, Coda, VIM, Emacs. Comparing to C# in this regard is not a good one. I find code completions / intelligence for JavaScript is very basic compared to something like C#.
Sure, and I accept that. But I would at the very least like to be able to open these files in Visual Studio and inspect them. It doesn't even let me to that much. It just gives me a lame error message about how I have to upgrade to Windows 8.1.