Nightmare.JS infinite scroll action

infinite_scrolling.js

var Nightmare = require('nightmare');
var vo = require('vo');
var nightmare = Nightmare({
  show: true
});

var run = function * () {
  yield nightmare.goto('http://scrollmagic.io/examples/advanced/infinite_scrolling.html');

  var previousHeight, currentHeight=0;
  while(previousHeight !== currentHeight) {
    previousHeight = currentHeight;
    var currentHeight = yield nightmare.evaluate(function() {
      return document.body.scrollHeight;
    });
    yield nightmare.scrollTo(currentHeight, 0)
      .wait(3000);
  }
  yield nightmare.end();
};

vo(run)(function(err) {
  console.dir(err);
  console.log('done');
});