Arduino delayMicroseconds equivalent

At the moment there isn't a direct replacement. You can do:

digitalWrite(pin, 1);
setTimeout(function() {
  digitalWrite(pin, 0);
  setTimeout(function() {
   ...
  }, 0.35);
},0.35);

or you can do:

digitalPulse(pin,1,0.35); 

Which will be substantially more accurate. This actually starts executing subsequent commands (apart from other digitalPulses) before the pulse has ended, so for something more accurate, you could try:

digitalPulse(pin,1,0.35); 
digitalPulse(pin,0,0.35); 

I'm trying to discourage people from writing code that delays (because then they start to get annoyed that Espruino isn't multithreaded), however I think delays do need to be added for this kind of thing - I've put a bug in for it, so hopefully I'll get around to it at some point.