<html>
<head>
<meta http-equiv="Content-Type" content="text/html" charset="utf-8" />
<title></title>
<link type="text/css" rel="stylesheet" />
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
</head>
<style>
#block{
position:absolute;
left:300px;
top:50px;
width:100px;
height:100px;
background-color:black;
}
#button{
position:absolute;
top:200px;
width:150px;
height:100px;
background-color:red;
}
</style>
<script>
$(function() {
var n = 1;
$("#button").on("click", function() {
var left = 300 * (n^= 1)+"px";
$('#block').animate({left : left}, 800);
})
});
</script>
<body>
<div id="button"></div>
<div id="block"></div>
</body>
</html>