Testing SW from Espruino book

I think your issue might just be how you copied the example code? In your code you have:

if (r.method == "POST" && r.query && r.query.led)

But the actual code is:

if (req.method=="POST" && r.query && r.query.led)

I think it'll work fine for you if you do that? Unfortuntely with these big bits of code it's hard to copy everything out without errors. If it's some help, I made the original code available online at https://github.com/espruino/making-things-smart - specifically I think https://github.com/espruino/making-things-smart/blob/master/experiment32.js is what you're after?