Tryit Editor v1.8

Source Code:

<!DOCTYPE html>
<html>
<head>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js">
</script>
<script> 
$(document).ready(function(){
  function aniDiv(){
    $("div:eq(0)").animate({width:"50%"},"slow");
    $("div:eq(0)").animate({width:"100%"},"slow",aniDiv);
  }
  aniDiv();
  $(".btn1").click(function(){
    $(":animated").css("background-color","red");
  });
});
</script>
</head>
<body>

<button class="btn1">Change color of the animated element</button>
<div style="background:blue;">Div 1</div>
<div style="background:green;">Div 2</div>
<div style="background:yellow;">Div 3</div>

</body>
</html>

Result:

W3Schools.com - Try it yourself

Edit the code above and click "Submit Code" to see the result.