[JS] 事件委托考察

erbing commented 5 years ago

<ul>
  <li class='target'>
      <span>test</span>
 </li>
</ul>

点击class为 target 的li可以 alert 出其所含内容（如上方代码点击弹出“test”）
在ul动态新增li元素的情况下，也要有相同效果
使用原生js实现，不使用jQuery\Vue\React\Angular 等框架

boybird commented 5 years ago


<body>

    <ul>
        <li class='target'>
            <span>test</span>
       </li>
      </ul>

    <script>
        function getEventTarget(e) {
            e = e || window.event;
            return e.target || e.srcElement;
        }
        document.getElementsByTagName('ul')[0].addEventListener('click', (e)=>{
            let target = getEventTarget(e);
            if(target.classList.contains("target")){
                alert("test");
            }
        })
    </script>
</body>

erbing commented 5 years ago

let appRom = document.getElementById('delegation')
let ulDom = appRom.children[0]

// 绑定方法
const handle = (dom, type, callback) => {
    dom.addEventListener(type,callback)
}

// 获取 target 对象方法 兼容
const getEventTarget = (e) => {
    e = e || window.event
    return e.target || e.srcElement
}

// 动态添加一个 btn 按钮
const createBtn = () => {
    let createBtnDom = document.createElement('button')
    createBtnDom.textContent = '添加'
    createBtnDom.className = 'add-btn'
    handle(createBtnDom, 'click', ()=>{
        let createLiDom = document.createElement('li')
        createLiDom.textContent = 'hello, li~' + Math.random()
        ulDom.appendChild(createLiDom)
    })
    return createBtnDom
}

// 执行 添加一个 btn 按钮 方法
let createBtnHtml = createBtn()
appRom.appendChild(createBtnHtml)

// 获得点击 target 的 innerHtml 方法
handle(appRom,'click',(e)=>{
    let curTarget = getEventTarget(e)
    if (curTarget.children && curTarget.children.length || curTarget.tagName == 'BUTTON') return false 
    return curTarget.innerHTML
})

Xiphin commented 5 years ago

<!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 id="delegation">
    <ul>
        <li class='target'>
            <span>test1</span>
       </li>
    </ul>
</div>
</body>
<script>
let appRom = document.getElementById('delegation')
let ulDom = appRom.children[0]

// 绑定方法
const handle = (dom, type, callback) => {
    dom.addEventListener(type,callback)
}

// 获取 target 对象方法 兼容
const getEventTarget = (e) => {
    e = e || window.event
    return e.target || e.srcElement
}

// 动态添加一个 btn 按钮
const createBtn = () => {
    let createBtnDom = document.createElement('button')
    createBtnDom.textContent = '添加'
    createBtnDom.className = 'add-btn'
    handle(createBtnDom, 'click', ()=>{
        let createLiDom = document.createElement('li')
        createLiDom.textContent = 'hello, li~' + Math.random()
        ulDom.appendChild(createLiDom)
    })
    return createBtnDom
}

// 执行 添加一个 btn 按钮 方法
let createBtnHtml = createBtn()
appRom.appendChild(createBtnHtml)

// 获得点击 target 的 innerHtml 方法
handle(appRom, 'click', (e)=>{
    let curTarget = getEventTarget(e)
    if (curTarget.children && curTarget.children.length || curTarget.tagName == 'BUTTON') return false 
    alert(curTarget.innerHTML)
})
</script>
</html>

erbing / logic-training

[JS] 事件委托考察 #2