title: How does the jquery animate function work internally?
body: <p>here is small code</p>
  
  <pre><code>&lt;div id="clickme"&gt;
  Click here
  &lt;/div&gt;
  &lt;img id="book" src="book.png" alt="" width="100" height="123"
  style="position: relative; left: 10px;" /&gt;
  
  $('#clickme').click(function() {
  $('#book').animate({
      opacity: 0.25,
      left: '+=50',
      height: 'toggle'
  }, 5000, function() {
      // Animation complete.
     });
  });
  </code></pre>
  
  <p>it is clear from the code left is increasing and opacity will be .25. how jquery manage to do so...does jquery internally execute a loop to increase the left and change the opacity until it becomes .25. need guidance. thanks</p>