syncNative.ts

import { PublicKey, TransactionInstruction } from "@solana/web3.js";
import { TOKEN_PROGRAM_ID } from "@solana/spl-token";
import { TokenInstruction } from "./instruction";

const BufferLayout = require("buffer-layout");

const dataLayout = BufferLayout.struct([BufferLayout.u8("instruction")]);

/**
 * Construct a SyncNative instruction
 *
 * @param account   Native account to sync lamports from
 * @param programId SPL Token program account
 *
 * @return Instruction to add to a transaction
 */
export function syncNative(
  account: PublicKey,
  programId = TOKEN_PROGRAM_ID
): TransactionInstruction {
  const keys = [{ pubkey: account, isSigner: false, isWritable: true }];

  const data = Buffer.alloc(dataLayout.span);
  dataLayout.encode({ instruction: TokenInstruction.SyncNative }, data);

  return new TransactionInstruction({ keys, programId, data });
}