<!DOCTYPE HTML>
<html>
<head>
<meta charset=utf-8 />
<title>UFO来了</title>
<script src="https://code.jquery.com/jquery-3.3.1.min.js"></script>
<style>
.box{
200px;
height: 1000px;
position:absolute;
background-color: rebeccapurple;
}
</style>
</head>
<body>
<button class="btnn">开始吧</button>
<div class="box"></div>
<script>
$('.btnn').on('click',function (){
$('.box').animate({'left':'1200px'},500,function () { <!--这里不明白为啥不能用‘right’：0px 欢迎给大佬解答-->
$(this).animate({'left':'0px'},500,function () {
$('.btnn').click()
})
})
})
</script>
</body>
</html>