Smart send a transaction using Jito dedicated endpoint

sendTxWithJito.ts

import { Connection, SendOptions } from '@solana/web3.js';
export type JitoRegion = 'mainnet' | 'amsterdam' | 'frankfurt' | 'ny' | 'tokyo';
export const JitoEndpoints = {
    mainnet: 'https://mainnet.block-engine.jito.wtf/api/v1/transactions',
    amsterdam: 'https://amsterdam.mainnet.block-engine.jito.wtf/api/v1/transactions',
    frankfurt: 'https://frankfurt.mainnet.block-engine.jito.wtf/api/v1/transactions',
    ny: 'https://ny.mainnet.block-engine.jito.wtf/api/v1/transactions',
    tokyo: 'https://tokyo.mainnet.block-engine.jito.wtf/api/v1/transactions',
};
export function getJitoEndpoint(region: JitoRegion) {
    return JitoEndpoints[region];
}
/**
 * Send a transaction using Jito. This only supports sending a single transaction on mainnet only.
 * See https://jito-labs.gitbook.io/mev/searcher-resources/json-rpc-api-reference/transactions-endpoint/sendtransaction.
 * @param args.serialisedTx - A single transaction to be sent, in serialised form
 * @param args.region - The region of the Jito endpoint to use
*/
export async function sendTxUsingJito({
    serializedTx,
    region = 'mainnet'
}: {
    serializedTx: Uint8Array | Buffer | number[];
    region: JitoRegion;
}) {
    let rpcEndpoint = getJitoEndpoint(region);
    let encodedTx = bs58.encode(serializedTx);
    let payload = {
        jsonrpc: "2.0",
        id: 1,
        method: "sendTransaction",
        params: [encodedTx]
    };
    let res = await fetch(`${rpcEndpoint}?bundleOnly=true`, {
        method: 'POST',
        body: JSON.stringify(payload),
        headers: { 'Content-Type': 'application/json' }
    });
    let json = await res.json();
    if (json.error) {
        throw new Error(json.error.message);
    }
    return json;
}

Thx! Updated

hi bro, how to build the serializedTx, only add tip instruction in it, right ? for example, one transfer tx, only contain transfer ins,if i want to send jito, i need add another ins for the tip, some thing wrong?