How can I get Visual Studio to source highlight .json source code?
Great news!
In CTP2 of Visual Studio 2013 Update 2 that was added a New JSON project item and editor
One more post New JSON editor features in Visual Studio 2013 Update 2 CTP2
Try to use Visual Studio Extension TextHighlighter:
VS 2010: TextHighlighterExtension
VS 2012: TextHighlighterExtension12
Navigate starting at the top menu bar,
TOOLS --> Options --> Text Editor --> File Extensions
Here you can add json as an entry, however, the Script Editor will not work at all, you can use Visual C++ editor experience which will provide very basic highlighting until Microsoft can get with the program and add some basic JSON support.