How to Transfer BTS Assets on BitShares Blockchain using Node.Js?

const { Apis, ChainConfig } = require("bitsharesjs-ws");
const { Aes, ChainStore, FetchChain, PrivateKey, TransactionBuilder, TransactionHelper } = require('bitsharesjs');
 
const https = require("https");
const agent = new https.Agent({
    rejectUnauthorized: false
});
 
BTS_TEST_NODE = "wss://api-us-testnet.61bts.com/ws";
BTS_NODE = "wss://api.61bts.com";
 
async function transferBTS(fromAccountName, toAccountName, amount, asset, memo, privateKeyWif, privateMemoKey, apiNode) {
    return new Promise(async (resolve, reject) => {
        try {
            await Apis.instance(apiNode, true,  4000, undefined, agent).init_promise;
            ChainConfig.setPrefix('BTS');
 
            await new Promise(resolve => setTimeout(resolve, 1000));
 
            const fromAccount = await FetchChain("getAccount", fromAccountName);
            const toAccount = await FetchChain("getAccount", toAccountName);
            const sendAsset = await FetchChain("getAsset", asset);
 
            if (!fromAccount) {
                throw new Error(`Unable to find account: ${fromAccountName}`);
            }
 
            if (!toAccount) {
                throw new Error(`Unable to find account: ${toAccountName}`);
            }
 
            if (!sendAsset) {
                throw new Error(`Unable to find asset: ${asset}`);
            }
 
            let memoObj;
            if (memo) {
                const nonce = TransactionHelper.unique_nonce_uint64();
                memoObj = {
                    from: fromAccount.get("options").get("memo_key"),
                    to: toAccount.get("options").get("memo_key"),
                    nonce: nonce,
                    message: Aes.encrypt_with_checksum(
                        PrivateKey.fromWif(privateMemoKey),
                        toAccount.get('options').get('memo_key'),
                        nonce,
                        new Buffer.from(memo, 'utf-8')
                    )
                };
            }
 
            const tr = new TransactionBuilder();
            const transferOp = tr.get_type_operation("transfer", {
                fee: {
                    amount: 0,
                    asset_id: "1.3.0"
                },
                from: fromAccount.get("id"),
                to: toAccount.get("id"),
                amount: {
                    amount: amount * Math.pow(10, sendAsset.get("precision")),
                    asset_id: sendAsset.get("id")
                },
                memo: memoObj
            });
 
            await tr.add_operation(transferOp);
            await tr.set_required_fees();
            tr.add_signer(PrivateKey.fromWif(privateKeyWif));
            const result = await tr.broadcast();
            resolve(result);
        } catch (error) {
            reject(error);
        }
    });
}