This is a copy of the full Jaxx codebase (minus third party libraries) of their wallet's back end; it does not contain any UI elements.
This is also found at https://jaxx.io/, but mirroring a version on GitHub allows for easier review and auditing capabilities.
You can follow the history of the Jaxx codebase by reviewing the commit history inside the sourceCode folder.
Each version of the Jaxx codebase can also be found as its own respective branch inside the repository.
I am not the author of this code and in no way affiliated with Jaxx.