Ray's are a useful tool for testing if geometry intersects a line of sight with Collider.rayCast. You can think of them as a point in space with a direction.

const actor = new ex.Actor({
  pos: ex.vec(200, 100),
  width: 100,
  height: 100,
  color: ex.Color.Red,

const ray = new ex.Ray(ex.vec(100, 100), ex.Vector.Right)

// Ray cast against the collider geometry, returns a point if intersects or null if not
const point = actor.collider.get().rayCast(ray)
// Vector(150, 100)