referencing another script in Unity

 a basic thing, I seem to always forget

two good threads on the topic:
https://forum.unity.com/threads/calling-function-from-other-scripts-c.57072/
https://forum.unity.com/threads/passing-a-game-object-reference-into-script.774251/

• I have a script KarmaPlayer that has a function I want to call
• changeKarma(int change)

this is a game pickup item that updates the karma value for the player

and then deactivates itself

//

using System.Collections;

using System.Collections.Generic;

using UnityEngine;

public class KarmaPickup : MonoBehaviour

{

    public int KarmaValue;

    KarmaPlayer karmaPlayer; //variable of type KarmaPlayer (the name of the script / class)

    void Start()

    {

        karmaPlayer = GameObject.Find("KarmaText(TMP)").GetComponent<KarmaPlayer>();

        //GameObject.Find("name of the game object").

        //finds the game object with the script / component

        //GetComponent<type>();

    }

    private void OnTriggerEnter2D(Collider2D collision)

    {

        if (karmaPlayer != null)

        {

            karmaPlayer.changeKarma(KarmaValue);

            this.gameObject.SetActive(false); //deactivate the pickup

        }

    }

}