how do i make player controller stop jumping infinite times?

 public class playercontroller : MonoBehaviour
     {
     
         public float Speed;
         public float JumpForce;
         private float moveInput;
     
         private Rigidbody2D rb;
     
         private bool facingRight = true;
     
         private bool isGrounded;
         public Transform groundcheck;
         public float checkRadius;
         public LayerMask whatIsGround;
     
         private int extraJumps;
         public int extraJumpsValue;
     
     
     
         void Start(){
     
             extraJumps = extraJumpsValue;
             rb = GetComponent<Rigidbody2D>();
         }
     
         void FixedUpdate() {
     
             isGrounded = Physics2D.OverlapCircle(groundcheck.position, checkRadius, whatIsGround);
     
             moveInput = Input.GetAxis("Horizontal");
             Debug.Log(moveInput);
             rb.velocity = new Vector2(moveInput * Speed, rb.velocity.y);
     
             if (facingRight == false && moveInput > 0) {
                 Flip();
             } else if (facingRight == true && moveInput < 0){
                 Flip();
             }
         }
     
         void Update(){
     
             if(isGrounded == true){
                 extraJumps = extraJumpsValue;}
     
             if(Input.GetKeyDown(KeyCode.UpArrow) && extraJumps > 0){
                 rb.velocity = Vector2.up * JumpForce;
             }
             else if(Input.GetKeyDown(KeyCode.UpArrow) && extraJumps == 0 && isGrounded == true){
                 rb.velocity = Vector2.up * JumpForce;
             }
         }
     
         void Flip() {
     
             if (isGrounded == true)
                 extraJumps = 0;
         
                 if (Input.GetKeyDown(KeyCode.UpArrow) && extraJumps > 0){
                 rb.velocity = Vector2.up * JumpForce;
                 extraJumps --;
             }
     
             facingRight = !facingRight;
             Vector3 Scaler = transform.localScale;
             Scaler.x *= -1;
             transform.localScale = Scaler;
         }
     
     }