Holding jump key player goes up forever.

I'm trying to add a double jump but I'm having issues. The double jump works but when I hold the jump key you go upwards forever. I dont understand coding can someone please help me. Im very new.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using UnityEngine.SceneManagement;
5.  
6.  
7. public class RainbowObserver : MonoBehaviour
8. {
9.     /// <summary>
10.     float dirX;
11.  
12.     [SerializeField]
13.     float jumpForce = 400f;
14.  
15.  
16.  
17.     bool doubleJumpAllowed = false;
18.     bool onTheGround = false;
19.  
20.     public int curHealth;
21.     public int maxHealth = 5;
22.  
23.     Animator animator;
24.     Rigidbody2D rb2d;
25.     SpriteRenderer spriteRenderer;
26.     private Collider2D coll;
27.     private enum State { idle, running, jumping, hurt }
28.     private State state = State.idle;
29.  
30.     bool isGrounded;
31.  
32.     [SerializeField]
33.     Transform groundCheck;
34.  
35.     [SerializeField]
36.     Transform groundCheckL;
37.  
38.     [SerializeField]
39.     Transform groundCheckR;
40.  
41.     [SerializeField]
42.     private float runspeed = 11f;
43.  
44.  
45.     [SerializeField] private float hurtForce = 10f;
46.  
47.  
48.  
49.  
50.     private void OnCollisionEnter2D(Collision2D other)
51.     {
52.         if (other.gameObject.tag == "Enemy")
53.  
54.         {
55.             if (state == State.jumping)
56.             {
57.                 Destroy(other.gameObject);
58.                 Jump();
59.  
60.             }
61.             else
62.             {
63.                 if (other.gameObject.transform.position.x > transform.position.x)
64.                 {
65.                     rb2d.velocity = new Vector2(-hurtForce, rb2d.velocity.y);
66.                 }
67.                 else
68.                 {
69.                     rb2d.velocity = new Vector2(hurtForce, rb2d.velocity.y);
70.                 }
71.             }
72.         }
73.  
74.     }
75.  
76.     void Start()
77.     {
78.         curHealth = maxHealth;
79.  
80.  
81.         animator = GetComponent<Animator>();
82.         rb2d = GetComponent<Rigidbody2D>();
83.         spriteRenderer = GetComponent<SpriteRenderer>();
84.  
85.  
86.     }
87.  
88.  
89.     private void Update()
90.     {
91.         if ((Physics2D.Linecast(transform.position, groundCheck.position, 1 << LayerMask.NameToLayer("Ground"))) ||
92.           (Physics2D.Linecast(transform.position, groundCheckL.position, 1 << LayerMask.NameToLayer("Ground"))) ||
93.           (Physics2D.Linecast(transform.position, groundCheckR.position, 1 << LayerMask.NameToLayer("Ground"))))
94.         {
95.             isGrounded = true;
96.         }
97.         else
98.         {
99.             isGrounded = false;
100.             animator.Play("Observer_rainbow_jump");
101.         }
102.  
103.         if (Input.GetKey("d"))
104.         {
105.             rb2d.velocity = new Vector2(runspeed, rb2d.velocity.y);
106.  
107.             if (isGrounded)
108.                 animator.Play("Observer_rainbow_run");
109.  
110.             spriteRenderer.flipX = false;
111.         }
112.         else if (Input.GetKey("a"))
113.         {
114.             rb2d.velocity = new Vector2(-runspeed, rb2d.velocity.y);
115.  
116.             if (isGrounded)
117.                 animator.Play("Observer_rainbow_run");
118.             spriteRenderer.flipX = true;
119.         }
120.         else
121.         {
122.             if (isGrounded)
123.                 animator.Play("Observer_rainbow_idle");
124.  
125.             rb2d.velocity = new Vector2(0, rb2d.velocity.y);
126.         }
127.  
128.    
129.  
130.         VelocityState();
131.         animator.SetInteger("state", (int)state);
132.  
133.  
134.         /// </summary>
135.         if (rb2d.velocity.y == 0)
136.             onTheGround = true;
137.         else
138.             onTheGround = false;
139.  
140.         if (onTheGround)
141.             doubleJumpAllowed = true;
142.  
143.         if (onTheGround && Input.GetKey("w"))
144.         {
145.             Jump();
146.         }
147.         else if (doubleJumpAllowed && Input.GetKey("w"))
148.         {
149.             Jump();
150.             doubleJumpAllowed = false;
151.         }
152.  
153.         dirX = Input.GetAxis("Horizontal") * runspeed;
154.         /// </summary>
155.  
156.  
157.         if (curHealth > maxHealth)
158.         {
159.             curHealth = maxHealth;
160.         }
161.  
162.         if (curHealth <= 0)
163.         {
164.             Die();
165.         }
166.     }
167.  
168.     /// </summary>
169.  
170.     void Jump()
171.     {
172.         rb2d.velocity = new Vector2(rb2d.velocity.x, 0f); ;
173.         rb2d.AddForce(Vector2.up * jumpForce);
174.         animator.Play("Observer_rainbow_jump");
175.         state = State.jumping;
176.     }
177.  
178.     /// </summary>
179.  
180.  
181.  
182.  
183.  
184.     private void VelocityState()
185.     {
186.         if (state == State.jumping)
187.         {
188.  
189.         }
190.         else if (Mathf.Abs(rb2d.velocity.x) > Mathf.Epsilon)
191.         {
192.             state = State.running;
193.         }
194.         else
195.         {
196.             state = State.idle;
197.         }
198.  
199.     }
200.  
201.     void Die()
202.     {
203.         Application.LoadLevel(Application.loadedLevel);
204.     }
205.  
206.     public void Damage(int dmg)
207.     {
208.         curHealth -= dmg;
209.     }
210. }

 

You are using GetKey for a jump button. It works for walking but shouldn't be used for jumping because it is being read every frame. You press a jump key and code applies upwards force. Because of gravity your character slows down and at some point velocity.y becomes 0 in mid air (right before the character starts falling) which leads to onTheGround becoming true. Because you are using GetKey and you are holding a key pressed, a jump happens mid-air. Use GetKeyDown for a jump. Also I think you should better use isGrounded to determine if you are on the ground instead.