Execute a Flashloan

import {
  Connection,
  Keypair,
  PublicKey,
  TransactionMessage,
  VersionedTransaction,
} from "@solana/web3.js";
import BN from "bn.js";
import { getFlashloanIx } from "@jup-ag/lend/flashloan";
import fs from "fs";
import path from "path";

const KEYPAIR_PATH = "/path/to/your/keypair.json";
const RPC_URL = "https://api.mainnet-beta.solana.com";
const ASSET = new PublicKey("EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v"); // USDC
const BORROW_AMOUNT = new BN(100_000_000); // 100 USDC

function loadKeypair(keypairPath: string): Keypair {
  const fullPath = path.resolve(keypairPath);
  const secret = JSON.parse(fs.readFileSync(fullPath, "utf8"));
  return Keypair.fromSecretKey(new Uint8Array(secret));
}

async function main() {
  // 1. Load user keypair and establish connection
  const userKeypair = loadKeypair(KEYPAIR_PATH);
  const connection = new Connection(RPC_URL, { commitment: "confirmed" });
  const signer = userKeypair.publicKey;

  // 2. Get the borrow and payback instructions
  const { borrowIx, paybackIx } = await getFlashloanIx({
    connection,
    signer,
    asset: ASSET,
    amount: BORROW_AMOUNT,
  });

  // 3. Define custom instructions that utilise the borrowed funds
  const customIxs = [
    // ... insert your custom logic here
  ];

  // 4. Assemble the transaction: Borrow -> Custom Logic -> Payback
  const instructions = [
    borrowIx,
    ...customIxs,
    paybackIx
  ];

  // 5. Build and sign transaction
  const latestBlockhash = await connection.getLatestBlockhash();
  const message = new TransactionMessage({
    payerKey: signer,
    recentBlockhash: latestBlockhash.blockhash,
    instructions,
  }).compileToV0Message(); // If your custom logic uses ALTs, pass them here

  const transaction = new VersionedTransaction(message);
  transaction.sign([userKeypair]);

  // 6. Send and confirm the transaction
  const signature = await connection.sendTransaction(transaction, {
    skipPreflight: false,
    maxRetries: 3,
    preflightCommitment: "confirmed",
  });

  await connection.confirmTransaction(
    { signature, ...latestBlockhash },
    "confirmed"
  );

  console.log("Flashloan successful! Signature:", signature);
}

main().catch(console.error);