Sending IOTA transaction in more granular way: API calls Prepare_transfer() and Send_transfer()

IOTA101_07CFD43B146C.js

// The snippet is a part of the IOTA Developer Essentials project. You can reach it at https://hribek25.github.io/IOTA101/
// Complete description and story behind the snippet is available at: https://hribek25.github.io/IOTA101/Allchapters_javascript.ipynb.html#07CFD43B146C
// Requirement: IOTA Javascript Library (!npm install iota.lib.js)

var IOTA = require('../../node_modules/iota.lib.js/lib/iota');
var NodeURL = "https://field.deviota.com:443";

var iota = new IOTA({
    'provider': NodeURL
});

var MySeed = "HGW9HB9LJPYUGVHNGCPLFKKPNZAIIFHZBDHKSGMQKFMANUBASSMSV9TAJSSMPRZZU9SFZULXKJ9YLAIUA";
var TargetAddress1 = "CXDUYK9XGHC9DTSPDMKGGGXAIARSRVAFGHJOCDDHWADLVBBOEHLICHTMGKVDOGRU9TBESJNHAXYPVJ9R9";
var TargetAddress2 = "CYJV9DRIE9NCQJYLOYOJOGKQGOOELTWXVWUYGQSWCNODHJAHACADUAAHQ9ODUICCESOIVZABA9LTMM9RW";

var NowIs = new Date(); //get a actual date & time - just to have some meaningfull info

// preparing transactions
var pt = {
    'address': TargetAddress1, //81 trytes long address
    'value': 0,
    'message': iota.utils.toTrytes('Here comes a first message. Now is ' + NowIs),
    'tag': 'HRIBEK999IOTA999TUTORIAL' //Up to 27 trytes
};

var pt2 = {
    'address': TargetAddress2, //81 trytes long address
    'value': 0,
    'message': iota.utils.toTrytes('Here comes a second message. Now is ' + NowIs),
    'tag': 'HRIBEK999IOTA999TUTORIAL999' //Up to 27 trytes
};

// Creating bundle, preparing inputs and finalizing bundle. It returns trytes of prepared TXs
var trytes;

iota.api.prepareTransfers(
    MySeed,               // Seed
    [pt, pt2],            // List of transactions
    {},                   // Options - security level / Inputs in case of value TXs, etc
    function (e, r) {     // Callback
        if (e) {
            console.log("Something went wrong: %s", e);
        }
        else { // Bundle is prepared
            trytes = r;
            console.log("Almost prepared bundle - tips and POW are still missing");
            console.log(trytes);
            console.log("Searching for tips and performing POW... Wait please...");
            iota.api.sendTrytes(
                trytes, // Trytes of prepared bundle from previous API call
                3,      // Depth
                14,     // MWM
                function (e, r) { // callback
                    if (e) {
                        console.log("Something went wrong: %s", e);
                    }
                    else { // if went OK, then it returns broadcasted TXs
                        console.log("Bundle was broadcasted.");
                        console.log("Final transactions were returned - including nonce (POW)");
                        console.log(r);
                    }
                }
            );
        }
    }
);