SegWit Private Key Sweep in NodeJS With BitcoinJS

gistfile1.txt

var bitcoin = require("bitcoinjs-lib");
var request = require("request");

//push transaction
function pushTX(pload, callback){
    request({
		url: "https://api.blockcypher.com/v1/btc/main/txs/push",
		method: "POST",
		json: true,
		headers: {"content-type": "application/json"},
		body: pload
		}, function(err, response, body){
            if(err){ 
			     //no response or error POST to chainso
			     console.log(body);
                 callback("failed");    
			} else {
                console.log(JSON.stringify(body));
                callback(JSON.stringify(body));
            };                
    });
};

function p2shWitSweep(privkey, addressout, callback){
    var NETWORK = bitcoin.networks.bitcoin;
    var keyPair = bitcoin.ECPair.fromWIF(privkey, NETWORK);
    var pubKey = keyPair.getPublicKeyBuffer();
    var pubKeyHash = bitcoin.crypto.hash160(pubKey);

    var redeemScript = bitcoin.script.witnessPubKeyHash.output.encode(pubKeyHash);
    var redeemScriptHash = bitcoin.crypto.hash160(redeemScript);

    var scriptPubKey = bitcoin.script.scriptHash.output.encode(redeemScriptHash);
    var address = bitcoin.address.fromOutputScript(scriptPubKey, NETWORK);

    var txb = new bitcoin.TransactionBuilder(NETWORK);
    
    request({
        url: "https://api.smartbit.com.au/v1/blockchain/address/"+address+"/unspent", 
        json: true
    }, function(err, resp, data){
        //fetch utxo
        var numutxo = data.unspent.length;
        console.log("utxos: "+numutxo);
        var totalVal = 0;
        for(i=0; i<numutxo; i++){  
                totalVal += data.unspent[i].value_int;
                txb.addInput(data.unspent[i].txid, data.unspent[i].n);
        }  
        //calc fee and add output address
        var satoshifees = numutxo * 7000;
        var amountToSend = totalVal - satoshifees;
        txb.addOutput(addressout, amountToSend);
        
        //sign each input
        for(i=0; i<numutxo; i++){  
                txb.sign(i, keyPair, redeemScript, null, data.unspent[i].value_int);
        }  
        
        //build tx
        var tx = txb.build();
        var tx_txid = tx.getId();
        var tx_raw = tx.toHex();
        var pload = {
            "tx": tx_raw.toString()
        };
        console.log("hextx: "+tx_raw);
        
        //broadcast
        pushTX(pload, function(result){
            console.log(result);
            callback(result);
            });
           
    });
}

p2shWitSweep("L28QQ43mQMPZj2vxFKbELC9rnudcmkwhjqHJ5tDNStqtbZkUeg7k", "17v9bcxrrKF4V2uyRtZR9QHRRcMFvG7pdq", function(txdata){
    console.log("Output: "+txdata);
});