关于前端:面试回顾DOM相关常见问题总结

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框架的利用宽泛，封装了 DOM 操作
DOM 实质——树（数据结构）

获取 DOM 节点

<!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>dom 演示 </title>

        <style>
            .container {border: 1px solid #ccc;}
            .red {color: red;}
        </style>
    </head>
    <body>
        <div id="div1" class="container">
            <p id="p1"> 一段文字 1</p>
            <p> 一段文字 2</p>
            <p> 一段文字 3</p>
        </div>
        <div id="div2">
            <img src="https://img3.mukewang.com/5a9fc8070001a82402060220-100-100.jpg"/>
        </div>
        <ul id="list">
        </ul>

        <script src="./dom-1.js"></script>
    </body>
</html>

const div1 = document.getElementById('div1')
console.log('div1', div1)

const divList = document.getElementsByTagName('div') // 汇合
console.log('divList.length', divList.length)
console.log('divList[1]', divList[1])

const containerList = document.getElementsByClassName('container') // 汇合
console.log('containerList.length', containerList.length)
console.log('containerList[1]', containerList[1])

const pList = document.querySelectorAll('p')
console.log('pList', pList)

const pList = document.querySelectorAll('p')
const p1 = pList[0]

// property 模式
const pList = document.querySelectorAll('p')
const p1 = pList[0]
p1.style.width = '100px'
console.log(p1.style.width)
p1.className = 'red'
console.log(p1.className)
console.log(p1.nodeName) // P
console.log(p1.nodeType) // 1

// attribute
p1.setAttribute('data-name', 'datetime')
console.log(p1.getAttribute('data-name') )
p1.setAttribute('style', 'font-size: 50px;')
console.log(p1.getAttribute('style') )

property：批改对象属性，不会体现到 html 构造中
attribute：批改 html 属性，会扭转 html 构造
两者都有可能引起 DOM 从新渲染

const div1 = document.getElementById('div1')
const div2 = document.getElementById('div2')

// 新建节点
const newP = document.createElement('p')
newP.innerHTML = 'this is newP'
// 插入节点
div1.appendChild(newP)

// 挪动节点
const p1 = document.getElementById('p1')
div2.appendChild(p1)

// 获取父元素
console.log(p1.parentNode)

// 获取子元素列表
const div1ChildNodes = div1.childNodes
console.log(div1.childNodes)
const div1ChildNodesP = Array.prototype.slice.call(div1.childNodes).filter(child => {if (child.nodeType === 1) {return true}
    return false
})
console.log('div1ChildNodesP', div1ChildNodesP)

div1.removeChild(div1ChildNodesP[0] )

正文完