Player Is infinite jumping

hi, just a simple question from a noob, how do I get this to stop jumping infinitely?

using UnityEngine;
using System.Collections;

public class PlayerController : MonoBehaviour
{

[HideInInspector]
public bool isFacingRight = true;
[HideInInspector]
public bool isJumping = false;
[HideInInspector]
public bool isGrounded = false;
public GameObject thing;
public GameObject floor;
public GameObject platform;

public float maxSpeed = 7.0f;
public float jumpForce = 650.0f;

public Transform groundCheck;
public LayerMask groundLayers;

private float groundCheckRadius = 0.2f;

void Start()
{ }



void Update()
{

    if (Input.GetButtonDown("Jump"))
    {
        if (isGrounded == true)
        {
            this.GetComponent<Rigidbody2D>().velocity = new Vector2(GetComponent<Rigidbody2D>().velocity.x, 0);
            this.GetComponent<Rigidbody2D>().AddForce(new Vector2(0, jumpForce));
        }

        if (floor == thing)
        {
            this.GetComponent<Rigidbody2D>().velocity = new Vector2(GetComponent<Rigidbody2D>().velocity.x, 0);
            this.GetComponent<Rigidbody2D>().AddForce(new Vector2(0, jumpForce));
        }
    }
}

void FixedUpdate()
{
    isGrounded = Physics2D.OverlapCircle
      (groundCheck.position, groundCheckRadius, groundLayers);

    float move = Input.GetAxis("Horizontal");
    this.GetComponent<Rigidbody2D>().velocity =
      new Vector2(move * maxSpeed, GetComponent<Rigidbody2D>().velocity.y);

    if ((move > 0.0f && isFacingRight == false) || (move < 0.0f && isFacingRight == true))
    {
        Flip();
    }
}

void Flip()
{
    isFacingRight = !isFacingRight;
    Vector3 playerScale = transform.localScale;
    playerScale.x = playerScale.x * -1;
    transform.localScale = playerScale;
}

}

Good day.

Thats not a question, you are asking to do the job for you. If you are not able to understand what this code does, go look at google for each variable and function, 1 by 1.

We are not code providers.

Bye!