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How to determine if an element has child nodes in jquery
- 青灯夜游Original
- 2022-05-25 13:52:592704browse
Method: 1. Use children() to get all child nodes under the element. The syntax "element object.children()" will return a jQ object containing child nodes; 2. Use length to detect the number of child nodes. Whether the number is 0, the syntax is "object.length==0". If the number is 0, there will be no child nodes, otherwise there will be.
The operating environment of this tutorial: windows7 system, jquery3.6.1 version, Dell G3 computer.
jquery method to determine whether an element has child nodes
1. Use children() to obtain all subsets under the element Element
children() method returns all direct children of the selected element.
$(selector).children()
will return a jQuery object containing all child nodes
2. Use the length attribute to determine whether the number of child nodes is 0
length The attribute can obtain the number of elements in the specified jQuery object
You only need to determine whether the number of child nodes obtained is 0
jQuery对象.length==0
The number of child nodes is 0. Then there are no child nodes
The number of child nodes is not 0, then there are child nodes
Implementation example:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<script src="js/jquery-3.6.1.min.js"></script>
<style>
.div,
div * {
display: block;
border: 2px solid lightgrey;
color: lightgrey;
padding: 5px;
margin: 15px;
}
</style>
<script>
$(document).ready(function() {
$("button").on("click", function() {
var len=$("ul").children().length;
console.log("ul元素中有子节点，个数为："+len);
$("ul").children().css({
"color": "red",
"border": "2px solid red"
});
});
});
</script>
</head>
<body class="ancestors">
<div style="width:500px;">div (父节点)
<ul>ul (指定元素)
<li>li (子节点1)
<span>span (孙节点1)</span>
</li>
<li>li (子节点2)
<span>span (孙节点2)</span>
</li>
<li>li (子节点3)
<span>span (孙节点3)</span>
</li>
</ul>
</div>
<button>检测ul元素是否有子节点</button>
</body>
</html> 
【Recommended learning: jQuery video tutorial, web front-end video】
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