How to Set Authority on Token Accounts or Mints

import {
  clusterApiUrl,
  Connection,
  PublicKey,
  Keypair,
  Transaction,
  sendAndConfirmTransaction,
} from "@solana/web3.js";
import {
  AuthorityType,
  createSetAuthorityInstruction,
  setAuthority,
} from "@solana/spl-token";
import bs58 from "bs58";
 
(async () => {
  // connection
  const connection = new Connection(clusterApiUrl("devnet"), "confirmed");
 
  // 5YNmS1R9nNSCDzb5a7mMJ1dwK9uHeAAF4CmPEwKgVWr8
  const feePayer = Keypair.fromSecretKey(
    bs58.decode(
      "588FU4PktJWfGfxtzpAAXywSNt74AvtroVzGfKkVN1LwRuvHwKGr851uH8czM5qm4iqLbs1kKoMKtMJG4ATR7Ld2",
    ),
  );
 
  // G2FAbFQPFa5qKXCetoFZQEvF9BVvCKbvUZvodpVidnoY
  const alice = Keypair.fromSecretKey(
    bs58.decode(
      "4NMwxzmYj2uvHuq8xoqhY8RXg63KSVJM1DXkpbmkUY7YQWuoyQgFnnzn6yo3CMnqZasnNPNuAT2TLwQsCaKkUddp",
    ),
  );
 
  const randomGuy = Keypair.generate();
  console.log(`random guy: ${randomGuy.publicKey.toBase58()}`);
 
  const mintPubkey = new PublicKey(
    "8mAKLjGGmjKTnmcXeyr3pr7iX13xXVjJJiL6RujDbSPV",
  );
 
  // authority type
 
  // 1) for mint account
  // AuthorityType.MintTokens
  // AuthorityType.FreezeAccount
 
  // 2) for token account
  // AuthorityType.AccountOwner
  // AuthorityType.CloseAccount
 
  // 1) use build-in function
  {
    let txhash = await setAuthority(
      connection, // connection
      feePayer, // payer
      mintPubkey, // mint account || token account
      alice, // current authority
      AuthorityType.MintTokens, // authority type
      randomGuy.publicKey, // new authority (you can pass `null` to close it)
    );
    console.log(`txhash: ${txhash}`);
  }
 
  // or
 
  // 2) compose by yourself
  {
    let tx = new Transaction().add(
      createSetAuthorityInstruction(
        mintPubkey, // mint acocunt || token account
        alice.publicKey, // current auth
        AuthorityType.MintTokens, // authority type
        feePayer.publicKey, // new auth (you can pass `null` to close it)
      ),
    );
    console.log(
      `txhash: ${await sendAndConfirmTransaction(connection, tx, [
        feePayer,
        alice /* fee payer + origin auth */,
      ])}`,
    );
  }
})();