callback json api

cb.old.js

var request = require('request');

var base_url = 'https://trade.cryptobroker.io/api/v2';
var bresponse = undefined

function get_summary(coin, exchange, cb) {
  var req_url = base_url + '/tickers/' + coin + exchange + '.json';
  request({uri: req_url, json: true}, function (error, response, body) {
  bresponse = body;
  cb()
 })
}

var lastprice = function get_ticker() {
     var lastprice = bresponse.ticker.last
     console.log(lastprice)
};

get_summary("btz", "btc", get_ticker());