How to move object side to side of screen width

Hello, I looked up a solution to move an object side to side horizontally.

 public float delta = 1.5f;
 public float speed = 2.0f;
 private Vector3 startPos;

 void Start()
 {
     startPos = transform.position;
 }

 void Update()
 {
     Vector3 v = startPos;
     v.x += delta * Mathf.Sin(Time.time * speed);
     transform.position = v;
 }

but instead of having a value "delta" I would rather it just move from the left side of the camera to the right side of the camera back & forth matter the size. How to accomplish t$$anonymous$$s?