BetterJump in Unity

BetterJump.cs

using System.Collections;
using UnityEngine;

public class BetterJump : MonoBehaviour {

  public float FallMultiplier = 2.5f;
  public float lowJumpMultiplier = 2f;

  RigidBody2D rb;

  void Start() {
    rb = GetComponent<RigidBody2D>();

  }

  void Update() {

    if (rb.velocity.y < 0) {
        rb.velocity += Vector2.up * Physics2D.gravity.y * (FallMultiplier - 1) * Time.deltaTime;
    } else if (rb.velocity.y > 0 && !Input.GetButton("Jump")) {
        rb.velocity += Vector2.up * Physics2D.gravity.y * (lowJumpMultiplier - 1) * Time.deltaTime;
    }
  }
 

}