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This article mainly introduces how to use DOM nodes to obtain page elements. Everything in the page document is a node: including element nodes, text nodes, attribute nodes, document nodes, and comment nodes. The following introduces two major methods of obtaining nodes:
(1) Obtaining nodes (including all nodes such as text nodes, element nodes, etc.)
1.parentNode: Get the parent node
2.childNodes: Get the child nodes, get each child node through the index value
3.firstChild: Get the first child node of the parent node
4.lastChild: Get the last child node of the parent node
5.nextSibling: Get the next sibling node adjacent to the child node
6.previousSibling: Get the adjacent child node The previous sibling node
7.attributes: Get the attribute node
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>由节点关系获取元素</title>
<style>
</style>
</head>
<body>
<div name="div1">
<p name='p1'>文本节点</p>
<p>2</p>
<ul>
<li>3</li>
<li id="li4">4</li>
<li>5</li>
<li>6</li>
</ul>
</div>
<section>7</section>
<main><span>8</span><i>9</i></main>
<script>
//注意换行和空格也属于结点，属于文本节点，按节点关系访问时需要考虑。属性节点无须考虑。
//1. parentNode获取div
console.log(document.querySelector('p').parentNode);
console.log(document.querySelector('p').parentNode.attributes[0]);
console.log(document.querySelector('p').parentNode.nodeName); //DIV
console.log(document.querySelector('p').parentNode.nodeValue); //null
console.log(document.querySelector('p').parentNode.nodeType); //1 元素节点
// 2.通过childNodes获取第一个p
console.log(document.querySelector('div').childNodes[1]);
console.log(document.querySelector('div').childNodes[1].firstChild.nodeName);
console.log(document.querySelector('div').childNodes[1].firstChild.nodeType); //2 文本节点
console.log(document.querySelector('div').childNodes[1].firstChild.nodeValue);
// 3.firstChild获取main中的第一个子节点
console.log(document.querySelector('main').firstChild);
// 4.lastChild获取main中的最后一个子节点
console.log(document.querySelector('main').lastChild);
// 5.nextSibling获取相邻下一个兄弟元素
console.log(document.querySelector('#li4').nextSibling.nextSibling);
// 6.previousSibling获取相邻上一个兄弟元素
console.log(document.querySelector('#li4').previousSibling.previousSibling);
// 总结：除parentNode外，其他方法谨慎选择，一旦代码格式有变，就会出现错误
// 通过nodeName获取节点名称
//通过nodeValue获取节点值
// 通过nodeType返回节点类型
</script>
</body>
</html>(2) Get the element node
1.parentElement: Get the parent element Node
2.children: Get the child element node, get each child element node through the index value
3.firstElementChild: Get the first child element node of the parent
4.lastElementChild: Get the last child element node of the parent
5.nextElementSibling: Get the adjacent next sibling element node
6.previousElementSibling: Get the adjacent previous sibling element Node
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>获取子元素节点</title>
</head>
<body>
<div>
<p>123</p>
<p>456</p>
<p>789</p>
</div>
<script>
//p标签总体算一个节点，内部的“123”不算
console.log(document.querySelector('div').childNodes);
console.log(document.querySelector('div').childNodes.length);
// 获取子元素节点
console.log(document.querySelector('div').children);
console.log(document.querySelector('div').children[1]);
console.log(document.querySelector('div').firstElementChild);
console.log(document.querySelector('div').firstElementChild.nextElementSibling);
console.log(document.querySelector('div').lastElementChild);
console.log(document.querySelector('div').lastElementChild.previousElementSibling);
console.log(document.querySelector('div').children[1].parentElement);
</script>
</body>
</html>Related recommendations: [JavaScript Video Tutorial]
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