$('.bxslider').bxSlider({
  onSliderLoad: function(){
    // do funky JS stuff here
    alert('Slider has finished loading. Click OK to continue!');
  },
  onSlideAfter: function(){
    // do mind-blowing JS stuff here
    alert('A slide has finished transitioning. Bravo. Click OK to continue!');
  }
});

<div class="bxslider">
  <div><img src="http://placehold.it/900x200&text=Slide 1" /></div>
  <div><img src="http://placehold.it/900x200&text=Slide 2" /></div>
  <div><img src="http://placehold.it/900x200&text=Slide 3" /></div>
</div>