Discussion on: Easy console.log() inside one liner functions

You could also wrap your function with a logger wrapper function. Ending up with something like:

nums.map(logged(num => <li key={num}>{num}</li>))

The function returned by your logged wrapper function would log inputs, outputs, whatever; as well as calling the passed function and returning its result. This way you could have consistent logging everywhere, and switch it off at a stroke just by modifying the logged function