?(1).事件捕获
从根元素往上传递??--- ---(由外到内)
(2).事件冒泡
从元素传递到它的根源素? --- --- (由内到外)
代码:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<!-- js中方法需要加() 如captrueMode() -->
<body>
<div class="buttonBox">
<button class="captrue" onclick="captrueMode('捕获模式')">捕获模式</button>
<button class="bubbling" onclick="bubblingMode('冒泡模式')">冒泡模式</button>
<div>当前模式为:(<span id="activeShow"></span>)</div>
</div>
<div id="six">
6
<div id="five">
5
<div id="four">
4
<div id="three">
3
<div id="two">
2
<div id="one">
1
</div>
</div>
</div>
</div>
</div>
</div>
</body>
<script>
// 获取元素
var elementOne = document.getElementById('one');
var elementTwo = document.getElementById('two');
var elementThree = document.getElementById('three');
var elementFour = document.getElementById('four');
var elementFive = document.getElementById('five');
var elementSix = document.getElementById('six');
const elementArr = [elementOne, elementTwo, elementThree, elementFour, elementFive, elementSix];
var modeFlag = false; // 默认 -- 冒泡模式
// 改变模式提示文字方法
const updateText = (text) => {
return document.getElementById('activeShow').innerText = text;
}
// ! 模式效果操作函数封装
const directionHandle = function (event) {
operateHandle(event, this);
}
// 元素添加监听控制事件方法封装
const addEventIsElement = function () {
elementArr.forEach(item => item.addEventListener('click', directionHandle, modeFlag));
}
// 元素删除监听控制事件方法封装
const removeEventIsElement = function () {
elementArr.forEach(item => item.removeEventListener('click', directionHandle, modeFlag));
}
// 切换为捕获模式
function captrueMode(mode) {
removeEventIsElement();
modeFlag = true, updateText(mode);
addEventIsElement();
}
// 切换为冒泡模式
function bubblingMode(mode) {
removeEventIsElement();
modeFlag = false, updateText(mode);
addEventIsElement();
}
bubblingMode('冒泡模式'); // 默认切换为冒泡模式
var showTime = 0;
var cancelShowTime = 1000;
// ! 改变属性
const updateClass = (thisDirection, isAccNumber = false) => {
if (isAccNumber) { showTime += 1000, cancelShowTime += 1000; }
setTimeout(() => { thisDirection.className = 'activeColor'; }, showTime);// 2s
setTimeout(() => { thisDirection.className = ''; }, cancelShowTime);
}
// !! 封装操作函数 -- x
const operateHandle = (event, thisDirection) => {
if (modeFlag) {
if (thisDirection.id === 'six') {
showTime = 0;
cancelShowTime = 1000;
updateClass(thisDirection);
} else {
updateClass(thisDirection, true);
}
} else {
if (event.srcElement.id === thisDirection.id) {
showTime = 0;
cancelShowTime = 1000;
updateClass(thisDirection);
} else {
updateClass(thisDirection, true);
}
}
}
</script>
</html>
<style lang="css">
#six {
width: 1200px;
height: 300px;
border: 1px solid #000;
text-align: center;
margin: auto;
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -110%);
background-color: #fff;
}
#five {
width: 1000px;
height: 250px;
border: 1px solid #000;
margin: auto;
background-color: #fff;
}
#four {
width: 800px;
height: 200px;
border: 1px solid #000;
margin: auto;
background-color: #fff;
}
#three {
width: 600px;
height: 150px;
border: 1px solid #000;
margin: auto;
background-color: #fff;
}
#two {
width: 400px;
height: 100px;
border: 1px solid #000;
margin: auto;
background-color: #fff;
}
#one {
width: 200px;
height: 50px;
border: 1px solid #000;
margin: auto;
background-color: #fff;
}
.activeColor {
background-color: red !important;
}
.captrue {
width: 120px;
height: 36px;
}
.buttonBox {
width: 1200px;
margin: auto;
}
.bubbling {
width: 120px;
height: 36px;
}
</style>
(3). 事件委托
事件委托:在需要的时候把事件交给别的元素来做 --- ---
优点 :(1) 减少内存消耗 ---- ---- 不用在每个标签上添加事件,只需获取父元素下的元素,绑定事件即可完成全部操作。
????????? ? (2) 具有动态绑定的效果 ---- ---- 在获取全部元素的条件下,不管增加或者减少的情况下都是一样的
?示例:在页面加载完的时候给元素添加上事件,然后来实现操作
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>JavaScript</title>
</head>
<body>
<ul id="list" style="width: 100px;margin:0;float: left;">
<li>1</li>
<li>2</li>
<li>3</li>
<li>4</li>
</ul>
<button style="float:left;" id="addli">添加一个 li</button>
<button style="float:left;" id="delli">删除一个 li</button>
<script>
window.onload = function () { 在页面加载完的时候获取到需要的元素
debugger
var the_ul = document.getElementById('list');
var the_li = the_ul.getElementsByTagName('li');
var sum = the_li.length
the_ul.onclick = function (e) {
console.log(e.target.innerHTML)
};
document.getElementById('addli').onclick = function () { 给需要的元素绑定上相应的事件
var newli = document.createElement("li"); 逻辑处理
newli.innerHTML = ++sum;
the_ul.appendChild(newli);
};
document.getElementById('delli').onclick = function () { 给需要的元素绑定上相应的事件
the_ul.firstElementChild.remove();逻辑处理
};
}
</script>
</body>
</html>