React seems to emphasize using regular javascript and existing NPM modules where possible. Superagent [1] seems to be a popular one, but you can find more on React's wiki [2].
If you start using a flux implementation like Redux, there are other interesting things you can do to handle api requests [3].
[1] https://github.com/visionmedia/superagent
[2] https://github.com/facebook/react/wiki/Complementary-Tools#d...