title: determine whether body's background-image (css) has been loaded
body: <p>Depending on some conditions, different background images are loaded:</p>
  
  <pre><code>$('body').css('background','url(image.png)');
  </code></pre>
  
  <p>Is there a way to determine whether the background image has loaded? I need to execute a function when the image has been loaded.</p>