jQuery closest()与实例

closest()是jQuery内置的一个方法，它可以返回DOM树中所选元素的第一个祖先。这个方法从当前元素开始向上追溯，寻找该元素的第一祖先。文档对象模型（DOM）是万维网联盟的一个标准。它定义了对DOM树中元素的访问。
语法:

$(selector).closest(para1, para2);

参数：它接受两个参数，具体如下–

para1：这指定了叙述DOM树中祖先搜索的元素。
para2: 这是一个可选的参数DOM元素，在其中找到一个匹配的元素。

返回值：它返回所选元素的第一个祖先。

jQuery代码显示closest()方法的工作：
代码 #1:
在下面的代码中，没有传递可选参数。

<html>
  
<head>
    <style>
        .main * {
            display: block;
            border: 2px solid lightgrey;
            color: grey;
            padding: 5px;
            margin: 15px;
        }
    </style>
    <script src="https://ajax.googleapis.com/ajax/libs/
               jquery/3.3.1/jquery.min.js"></script>
    <script>
    <!-- here is the script code for performing the method -->
         $(document).ready(function() {$ ("span").closest("ul").css({
                "color": "green",
                "border": "2px solid green"
            });
        });
    </script>
</head>
  
<body class="main">
    This is great-great grand parent element !
    <div style="width:600px;">
        This is great grand parent element !
        <ul>
            This is the second ancestor element !
            <ul>
                <!-- This element will be selected -->
                This is first ancestor element !
                <li>This is direct parent !
                <span>This is span the child element !</span>
                </li>
            </ul>
        </ul>
    </div>
</body>
  
</html>

输出:
jQuery closest()与实例
代码 #2:
在下面的代码中，可选参数被传递给方法。

<html>
  
<head>
    <style>
        .main * {
            display: block;
            border: 2px solid lightgrey;
            color: grey;
            padding: 5px;
            margin: 15px;
        }
    </style>
    <script src="https://ajax.googleapis.com/ajax/libs/
             jquery/3.3.1/jquery.min.js"></script>
    <script>
         $(document).ready(function() { <!--Here among dom id first ancestor will select --> var item = document.getElementById("dom");$ ("li").closest("ul", item).css({
                "color": "green",
                "border": "2px solid green"
            });
        });
    </script>
</head>
  
<body class="main">
    This is great-great-grandparent !
    <div style="width:500px;">
        div (great-grandparent)
        <ul id="dom">
            This is second ancestor !
            <ul id="dom">
                This is first ancestor !
                <li>This is direct parent !
                <span>This is span the child one !</span>
                </li>
            </ul>
        </ul>
    </div>
</body>
  
</html>

输出:
jQuery closest()与实例