关于前端:vue基础知识

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue"></script>
    <style>
        .color{color: red;}
        .style{font-style: italic;}
        .size{font-size: 20px;}
        .weight{font-weight: bold;}
    </style>
</head>
<body>
    <div id="app">
        <!-- v-clock 解决闪动 -->
        <div v-clock>{{clockData}}</div>
        <div v-text="msg">111</div>
        <div v-html="msg">111</div>
        <!-- v-bind 绑定属性,缩写: -->
        <p :title="titleMsg ||'this is my title'">show me</p>
        <!-- v-on 绑定事件,缩写 @ -->
        <button @click="clickTest">click me</button>
        <!-- 事件修饰符 -->
        <!-- .stop 阻止冒泡 -->
        <div @click="clickFa">
            <div @click.stop="clickTest">
                <button @click="clickChild">stop child</button>
                <p>father2</p>
            </div>
            <p>father1</p>
        </div>
        <!-- .prevent 阻止默认行为 -->
        <a href="http://www.baidu.com" @click.prevent="clickTest">aaa</a>
        <!-- .capture 实现捕捉 -->
        <div @click.capture="clickFa">
            <button @click="clickChild">prevent child</button>
            <p>father</p>
        </div>
        <!-- .self 只点击以后元素才触发 
            并不会对冒泡有本质影响,只是加了.self 的那一层只有点击本人时才会触发
        -->
        <div @click="clickFa">
            <div @click.self="clickTest">
                <button @click="clickChild">self child</button>
                <p>father2</p>
            </div>
            <p>father1</p>
        </div>
        <!-- .once 只触发一次 -->
        <a href="http://www.baidu.com" @click.prevent.once="clickTest">aaaOnce</a><br />
        <!-- v-model 双向绑定 -->
        <!-- 不是双向数据流,只是语法糖 -->
        单向绑定 <input type="text" :value="inpMsg">
        双向绑定 <input type="text" v-model="inpMsg">
        <!-- class -->
        <p :class="['color','size',{'weight':flag}]">show class</p>
        <p :class="classObj">show class</p>
        <!-- style -->
        <p :style="styleObj1">show style</p>
        <p :style="[styleObj1,styleObj2]">show style</p>
        <!-- v-for -->
        <ul>
            <li v-for="(item,index) in list">{{index}} - {{item}}</li>
            <li v-for="(val,key,i) in obj">{{key}} : {{val}} -- {{i}}</li>
            <li v-for="count in 4">{{count}}</li>
        </ul>
        <!-- key 惟一标识符 -->
        <p>
            <span>val</span>
            <input type="text" v-model="name">
        </p>
        <button @click="add">ADD</button>
        <ul>
            <li v-for="item in valList" :key="item.id"><input type="checkbox">{{item.id}} - {{item.name}}</li>
        </ul>
        <!-- v-if(会操作 dom)/v-show -->
        <button @click="change">change flag</button>
        <p v-show="flag">v-show</p>
        <p v-if="flag">v-if</p>
        <!-- computed -->
        <p>{{fulldata}}</p>
    </div>
    <script>
        var vm = new Vue({
            el:'#app',
            data:{
                clockData:'123333',
                msg:'<h1>222</h1>',
                titleMsg:'title',
                inpMsg:'input value',
                flag:false,
                classObj:{color:true,style:true,size:true,weight:true},
                styleObj1:{color:'red','font-size':'20px'},
                styleObj2:{'font-weight':'bold'},
                list:[2,4,6,8,10],
                obj:{a:1,b:2,c:3},
                id:3,
                name:'',
                valList:[{id:1,name:'qq'},
                    {id:2,name:'cc'},
                    {id:3,name:'sxq'},
                ]
            },
            methods: {clickTest(){console.log('click')},
                clickFa(){console.log('Fa')},
                clickChild(){console.log('child')},
                add(){this.valList.unshift({id:++this.id,name:this.name})},
                change(){this.flag=!this.flag}
            },
            // 1. 一对多
            watch:{
                flag:{ // 此写法能够在渲染实现后,就触发一次
                    handler(newData,oldData){console.log(newData,oldData,'newData,oldData--')
                    },
                    immediate:true
                },
                // 或
                // 'flag'(newData,oldData){//     console.log(newData,oldData,'newData,oldData--')
                // }
            },
            // 1. 表白更清晰
            // 2. 缓存
            // 3. 多对一
            computed:{'fulldata'(){return this.id + '---' + this.name;}
            }
        })
    </script>
</body>
</html>

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