Doesn't connect when being used in react native #2

I have followed the instructions, fortunately, the app doesn't crash however anything happens.Here is my code is written in react native.
`
import wamp from 'wamp.js';
var connection = new wamp.Connection({url: 'http://localhost:3009', realm: 'realm1'});
connection.onopen = function (session) {

      // 1) subscribe to a topic
      function onevent(args) {
          console.log("Event:", args[0]);
      }
      session.subscribe('onNewData', onevent);
  };

connection.open();
`