<!DOCTYPE html>
<html>
<head>
<script src="/lib/jquery-1.12.2.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>