Thanks to a prior solution created by Steve Troughton-Smith for Lua, I was able to hack together an Xcode Plug-In (yeah, those still exist) for 10.1.

TypeScript repo is here at github.

To install, quit Xcode. Run setup.sh to add the xclangspec and ideplugin info to your ~/Library/Developer/Xcode folders. Then launch Xcode, agree to allow the plug-in to run, and then add your ts files.

The file inspector will still say they’re MPEG-2 Transport Stream files but you’ll be able to see the text, the text will be formatted, and you can use Xcode to search for content within the files. Let me know if it works for you.

The xcplugin and the xclangspec were easy to put together, because I just riffed on JavaScript’s syntax. Other languages will take a bit more work because you have to set up a list of keywords and their characters and syntax coloring rules, which may or may not lend themselves to easy lexer support.