Imagine your favorite celebrity posting a photograph on Facebook. Now you go and like the image and then you suddenly see that lets check out the comments too.
Now while you are browsing over comments you see that likes count increased by count 100 since you liked the picture. Yes and there was no reload of the page, just somehow magically the count changed. This magic my friend is reactjs.
So it is not only the ReactJS, any framework/library which has the base as Javacript can be automated using the protractor.