Wrong onscreenready Example

main.js

bb.init({
  onscreenready: function (element, id) {
    if (id == "main") {
      var item = document.createElement('div');
      item.setAttribute('data-bb-type','item');
      item.setAttribute('data-bb-title','my title');
      item.innerHTML = 'my description';
      item.setAttribute('data-bb-img','foo.png');

      document.getElementById('mylist').appendItem(item);

      $("#button").css("display", "block");
    }
  }
});