How to Set Authority on Token Accounts or Mints

import { Connection, Keypair, LAMPORTS_PER_SOL } from "@solana/web3.js";
import {
  AuthorityType,
  setAuthority,
  createMint,
  getOrCreateAssociatedTokenAccount
} from "@solana/spl-token";

(async () => {
  const connection = new Connection("http://127.0.0.1:8899", "confirmed");

  // Setup fee payer
  const feePayer = Keypair.generate();

  const airdropSignature = await connection.requestAirdrop(
    feePayer.publicKey,
    LAMPORTS_PER_SOL
  );
  await connection.confirmTransaction(airdropSignature);

  // Create a new random authority
  const newAuthority = Keypair.generate();
  console.log(`New Authority Public Key: ${newAuthority.publicKey.toBase58()}`);

  // Create a new mint
  console.log("Creating new mint...");
  const mint = await createMint(
    connection,
    feePayer,
    feePayer.publicKey,
    feePayer.publicKey,
    9
  );
  console.log(`Mint created: ${mint.toBase58()}`);

  // Create token account
  console.log("Creating token account...");
  const tokenAccount = await getOrCreateAssociatedTokenAccount(
    connection,
    feePayer,
    mint,
    feePayer.publicKey
  );
  console.log(`Token account created: ${tokenAccount.address.toBase58()}`);

  // 1. Change Mint Authority (MintTokens)
  console.log("\n1. Changing Mint Authority...");
  const mintAuthTx = await setAuthority(
    connection,
    feePayer,
    mint,
    feePayer,
    AuthorityType.MintTokens,
    newAuthority.publicKey // Set to null to permanently disable minting
  );
  console.log(`Mint authority changed. Tx: ${mintAuthTx}`);

  // 2. Change Freeze Authority
  console.log("\n2. Changing Freeze Authority...");
  const freezeAuthTx = await setAuthority(
    connection,
    feePayer,
    mint,
    feePayer,
    AuthorityType.FreezeAccount,
    newAuthority.publicKey // Set to null to permanently disable freezing
  );
  console.log(`Freeze authority changed. Tx: ${freezeAuthTx}`);

  // Example of revoking authority (setting to null)
  console.log("\n3. Revoking Mint Authority...");
  const revokeMintAuthTx = await setAuthority(
    connection,
    feePayer,
    mint,
    newAuthority, // must be signed by current authority
    AuthorityType.MintTokens,
    null // Setting to null revokes the authority
  );
  console.log(`Mint authority revoked. Tx: ${revokeMintAuthTx}`);
})();