"Otto DIY" smooth movements adaptation for Espruino

I guess you might find what I did for the laser cutter helpful: http://forum.espruino.com/conversations/821/#26363

It was for steppers, not servos - but the same should apply for more than one servo:

function moveTo(p, speed, callback) {
  var dx = x.pos - p[0];
  var dy = y.pos - p[1];
  var d = Math.sqrt(dx*dx+dy*dy);
  var time = d*speed;
  x.move(p[0],time, undefined);
  y.move(p[1],time, callback);
}

You can just call move on multiple servo instances, having the same time period for all of them - and then callback when one has finished (they will all finish at the same time). Note the code above is trying to keep a constant speed, not movement time.

Getting that to work as a promise, with a set time perios should be something like:

function moveTo(p, time) {
 return new Promise(function(resolve){
  x.move(p[0],time, undefined);
  y.move(p[1],time, resolve);
 }
}

moveTo([0,0],1000).then(x=>{
  moveTo([1,1],1000)
})...etc