prophet.js

var previousDistance = Number.MAX_VALE;
var dir = 0;
function tick(distance) {
  console.log('distance:', distance);
  var randomTurn = 2 - Math.round(Math.random() * 4);
  console.log(randomTurn);
  if (distance >= previousDistance) dir += randomTurn;
  var directions = ['up', 'down', 'left', 'right'];
  var direction = directions[dir % directions.length];
  previousDistance = distance;
  return direction;
}