Make an NPC turn around when it reaches a point

Hey everyone. I have an NPC that is walking back and forth between two points, but he always faces the same direction. How can I get the NPC to turn around and face the direction he's walking once he reaches the point. Here's my script, thanks in advance!

 #pragma strict
 var pointB : Vector3;
 
 
 function Start () {
     var pointA = transform.position;
     while (true) {
         yield MoveObject(transform, pointA, pointB, 3.0);
         yield MoveObject(transform, pointB, pointA, 3.0);
     }
 }
 
 
 function MoveObject (thisTransform : Transform, startPos : Vector3, endPos : Vector3, time : float) {
     var i = 0.0;
     var rate = 1.0/time;
     while (i < 1.0) {
         i += Time.deltaTime * rate;
         thisTransform.position = Vector3.Lerp(startPos, endPos, i);
         yield; 
     }
 }