$(".item-b").parents(".div",".first-div").css("border","1px solid red");???
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-type" content="text/html; charset=utf-8" />
<title></title>
<style>
.left {
width: auto;
height: 350px;
}
.left div {
width: 350px;
height: 150px;
padding: 5px;
margin: 5px;
float: left;
background: #bbffaa;
border: 1px solid #ccc;
}
span {
color: blue;
}
</style>
<script src="https://www.imooc.com/static/lib/jquery/1.9.1/jquery.js"></script>
</head>
<body>
<h2>parents方法()</h2>
<div class="left first-div">
<div class="div">
<ul class="level-2">
<!-- A -->
<li class="item-a">A</li>
<!-- B -->
<li class="item-b">B
<ul class="level-3">
<li class="item-1">1</li>
<li class="item-2">2</li>
<li class="item-3">3</li>
</ul>
</li>
<!-- C -->
<li class="item-c">C</li>
</ul>
</div>
<div class="div">
<ul class="level-2">
<!-- A -->
<li class="item-a">A</li>
<!-- B -->
<li class="item-b">B
<ul class="level-3">
<li class="item-1">1</li>
<li class="item-2">2</li>
<li class="item-3">3</li>
</ul>
</li>
<!-- C -->
<li class="item-c">C</li>
</ul>
</div>
</div>
<button>点击：parents无参数</button>
<button>点击：parents传递选择器</button>
<script type="text/javascript">
$("button:first").click(function() {
$(".item-b").parents(".div",".first-div").css("border","1px solid red");
})
</script>
<script type="text/javascript">
$("button:last").click(function() {
//找到当前元素的所有祖辈元素,筛选出class="first-div"的元素
//并且附上一个边
$('.item-b').parents('.first-div').css('border', '2px solid blue')
})
</script>
</body>
</html>
