I had Visual Studio 2015 CTP 4 installed and now CTP6 - In both cases it was missing Javascript support.
Not showing syntax highlighting for .js file
Intellisense not working for .js files
Also when i go to tools/options/Text Editor - Javascript language section is missing. See image and its comparison with VS2013.
Image At: https://social.msdn.microsoft.com/Forums/getfile/615484