Bouncing character like on a pogo stick

I am just using a basic player movement script that I found online, but what I am looking to do is modify this script so the character is constantly jumping. As if the character were bouncing on a pogo stick. I was thinking of just adding a loop that constantly press my jump button, but I don't think that's very efficient.

Any ideas? (below is my code)

var speed : float = 6.0;

var jumpSpeed : float = 8.0;

var gravity : float = 20.0;

private var moveDirection : Vector3 = Vector3.zero;

function Update() {

 var controller : CharacterController = GetComponent(CharacterController);
 
 if (controller.isGrounded) {
     // We are grounded, so recalculate
     // move direction directly from axes
     moveDirection = Vector3(Input.GetAxis("Horizontal"), 0,
                             Input.GetAxis("Vertical"));
     moveDirection = transform.TransformDirection(moveDirection);
     moveDirection *= speed;
     
     if (Input.GetButton ("Jump")) {
         moveDirection.y = jumpSpeed;
     }
 }

 // Apply gravity
 moveDirection.y -= gravity * Time.deltaTime;
 
 // Move the controller
 controller.Move(moveDirection * Time.deltaTime);

}