Jumping NavMeshAgent

Sorry for my english.
I need to my character with NavMeshAgent on it move towards the target, and when i press "Space" character will jump and continued to move towards the target.



i tried to use this code but after i am press "Space" my characrer stops moving, and if i press space several times, character flies up and stops moving towards the target, and only when he falls down he continues to move towards the target.

private NavMeshAgent agent;
public LayerMask groundMask;
private Rigidbody rb;

public Transform target;
public float jumpForce;
public float groundRadius;
public bool isGrounded;
public Collider[] ground;


void Start()
{
agent = GetComponent<NavMeshAgent>();

agent.autoBraking = false;

agent.destination = target.position;

rb = GetComponent<Rigidbody>();
}

void Update()
{
ground = Physics.OverlapSphere(transform.position, groundRadius, groundMask);

if (ground.Length == 0)
{
isGrounded = false;
agent.enabled = false;
}
else{
isGrounded = true;
agent.enabled = true;
agent.destination = target.position;
}

if(Input.GetKeyDown(KeyCode.Space) && isGrounded)
Jump();

}

void Jump()
{
isGrounded = false;

agent.enabled = false;

rb.AddForce(transform.up * jumpForce, ForceMode.Impulse);
agent.velocity = rb.velocity;
}