How busy is the CPU?

Notice the 'funny' & and | in the set

var pulse = function(led,stp) {
  var ity = 0;
  return function(){
    analogWrite(led, 
      (ity += stp) < 0
       ? ity = 0 & (stp = - stp)
       : (ity > 1)
         ? ity = (stp = - stp) | 1
         : ity
     );
    console.log(ity);
  };
};

Has the issue with repeating 0 and 1 with 1 / stp being a whole number, but working for all other stp. Changing the comparison from < and > to <= and >= works just the other way round.