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8. Event handling - event modifier

2022-07-20 08:40:00 【Where the wind falls】

1. The basic use of events

1. Use v-on:xxx perhaps @xxx The binding event , among xxx Is the event name

2. Event callback needs to be configured in methods in , Eventually it will be vm On

3.methods Functions configured in , Don't use arrow functions , otherwise this It's not vm 了

4.methods Functions configured in , It's all about being Vue Managed functions ,this The direction is vm Or component instance object

[email protected]="demo" and @click="demo($event)" The effect is consistent , But the latter can be passed on

2. Event modifier

1.prevent： Block default events

2.stop： Stop the event from bubbling （ Commonly used ）

3.once： The event is triggered only once （ Commonly used ）

4.capture： Use the capture mode for events ;

5.self： Only event.target Is the element of the current operation

6.passive： The default behavior of the event executes immediately , There is no need to wait for the event callback to complete 

<!DOCTYPE html>
<html lang="en">
<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>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/vue.js"></script>
    <style>
        * {
            margin-top: 20px;
        }
        .demo1{
            height: 50px;
            background-color: skyblue;
        }
        .box1{
            padding: 5px;
            background-color: skyblue;
        }
        .box2{
            padding: 5px;
            background-color: orange;
        }
        .list{
            width: 200px;
            height: 200px;
            background-color: peru;
            overflow: auto;
        }
        li{
            height: 100px;
        }
    </style>
</head>
<body>
    <div id="root">
        <h2> Welcome to {
   {name}} Study </h2>
        <!--  Block default events  -->
        <a href="http://www.atguigu.com" @click.prevent="showInfo"> Click I block default events </a>

        <!--  Stop the event from bubbling --- Commonly used  -->
        <div class="demo1" @click="showInfo">
            <button @click.stop="showInfo"> I'll stop the bubble </button>
        </div>

        <!--  The event is triggered only once （ Commonly used ） -->
        <button @click.once="showInfo"> Click I only trigger one event </button>

        <!--  Use the capture mode for events  -->
        <div class="box1" @click.capture="showMsg(1)">
            div1
            <div class="box2" @click="showMsg(2)">
                div2
            </div>
        </div>

        <!--  The default behavior of the event executes immediately , There is no need to wait for the event callback to complete ; -->
        <!--  When scrolling the mouse wheel, trigger the default behavior first, and then execute the event callback  -->
        <ul @wheel.passive="demo" class="list">
            <li>1</li>
            <li>2</li>
            <li>3</li>
            <li>4</li>
        </ul>
    </div>
</body>
</html>
<script type="text/javascript">
    Vue.config.productionTip = false //  prevent vue Generate production prompts at startup 

    new Vue({
        el: "#root",
        data: {
            name: " Silicon Valley "
        },
        methods: {
            showInfo(e) {
                alert(" Hello, classmate der！")
                console.log(e)
            },
            showMsg(msg){
                console.log(msg)
            },
            demo(){
                for (let i = 0; i < 100000; i++) {
                    console.log('#')
                }
                console.log(' The default behavior is executed immediately ')
            }
        }
    })
</script>

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本文为[Where the wind falls]所创，转载请带上原文链接，感谢
https://yzsam.com/2022/201/202207190503370520.html

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