Surprisingly, their implementation of `react-fs` doesn't use synchronous node `fs.readFileSync`… instead, they're doing some trickery (throwing a Promise!) to make `react-fs` appear synchronous when it's really asynchronous! https://github.com/facebook/react/blob/master/packages/react...

https://github.com/facebook/react/blob/master/packages/react...

However, I agree that using async/await would be better.