1.closest
1.1 功能详解
功能：返回当前节点最近的匹配选择符的祖先元素
var el = document.querySelector(childSelector).closest(parentSelector);
如下网页结构：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>closest</title>
</head>
<body>
<div class="con">
<span class="list"></span>
</div>
</body>
</html>
1.1.1 比如想要通过.list来选取.con
document.querySelector('.list').closest('.con');
结果：会返回
.con元素
1.1.2 如果childSelector参数和parentSelector参数相同
document.querySelector('.list').closest('.list');
结果：会返回
.list元素
1.1.3 如果parentSelector没找到
document.querySelector('.list').closest('.tip');
结果：会返回
null
1.2 应用案例
需求说明：用事件委托来获取当前点击区块的
data-option值
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
</head>
<body>
<div class="con">
<div class="con-list" data-option="1">
<span class="con-list-name">小明</span>
<span class="con-list-gender">男</span>
</div>
<div class="con-list" data-option="2">
<span class="con-list-name">小华</span>
<span class="con-list-gender">男</span>
</div>
<div class="con-list" data-option="3">
<span class="con-list-name">小美</span>
<span class="con-list-gender">女</span>
</div>
</div>
<script>
document.querySelector('.con').addEventListener('click', function(e) {
console.log(e.target.closest('.con-list').dataset.option);
})
</script>
</body>
</html>
