10.js

const nearestAsteroidsByAngle = pipe(
  asteroids.filter(mkNe(laserPos)),
  groupBy(mkCalcAngle(laserPos)),
  mapValues(ps => ps.sort((p1, p2) => distToLaser(p1) - distToLaser(p2))),
  intoMap(),
);

pipe(
  cycle([...nearestAsteroidsByAngle.keys()].sort((a, b) => a - b)),
  skipWhile(a => a < -Math.PI/2),
  map(angle => nearestAsteroidsByAngle.get(angle)),
  filter(nearest => nearest.length),
  map(nearest => nearest.shift()),
  take(200),
  last(),
  p => log(p[0] * 100 + p[1]),
);