instantiating a projectile continually over time

I have a prefab moving left to right across the screen I can get it to shoot at the player/camera on the z axis once at the start but I would like to have the enemy object keep shooting at the player as it moves across the screen. I have tried different things but I can't seem to get it to work. Any help would be great.

var projectile : Rigidbody; var initialSpeed = 20.0;

function Update() {

     {
     // create a new projectile, use the same position and rotation as the Launcher.
     var instantiatedProjectile : Rigidbody = Instantiate (projectile, transform.position, transform.rotation);
         
     // Give it an initial forward velocity. The direction is along the z-axis of the missile launcher's transform.
     instantiatedProjectile.velocity = transform.TransformDirection(Vector3 (0, initialSpeed, 0));

     // Ignore collisions between the missile and the character controller
     Physics.IgnoreCollision(instantiatedProjectile.collider, transform.root.collider);
     
 }

}