一、基本列表

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8" />
        <title>基本列表</title>
        <script type="text/javascript" src="../js/vue.js"></script>
    </head>
    <body>
        <!-- 
                v-for指令:
                        1.用于展示列表数据
                        2.语法:v-for="(item, index) in xxx" :key="yyy"
                        3.可遍历:数组、对象、字符串(用的很少)、指定次数(用的很少)
        -->
        <!-- 准备好一个容器-->
        <div id="root">
            <!-- 遍历数组 -->
            <h2>人员列表(遍历数组)</h2>
            <ul>
                <li v-for="(p,index) of persons" :key="index">
                    {{p.name}}-{{p.age}}
                </li>
            </ul>

            <!-- 遍历对象 -->
            <h2>汽车信息(遍历对象)</h2>
            <ul>
                <li v-for="(value,k) of car" :key="k">
                    {{k}}-{{value}}
                </li>
            </ul>

            <!-- 遍历字符串 -->
            <h2>测试遍历字符串(用得少)</h2>
            <ul>
                <li v-for="(char,index) of str" :key="index">
                    {{char}}-{{index}}
                </li>
            </ul>
           
            <!-- 遍历指定次数 -->
            <h2>测试遍历指定次数(用得少)</h2>
            <ul>
                <li v-for="(number,index) of 5" :key="index">
                    {{index}}-{{number}}
                </li>
            </ul>
        </div>

        <script type="text/javascript">
            Vue.config.productionTip = false
            
            new Vue({
                el:'#root',
                data:{
                    persons:[
                        {id:'001',name:'张三',age:18},
                        {id:'002',name:'李四',age:19},
                        {id:'003',name:'王五',age:20}
                    ],
                    car:{
                        name:'奥迪A8',
                        price:'70万',
                        color:'黑色'
                    },
                    str:'hello'
                }
            })
        </script>
</html>

二、key的原理

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8" />
        <title>key的原理</title>
        <script type="text/javascript" src="../js/vue.js"></script>
    </head>
    <body>
        <!-- 
                面试题:react、vue中的key有什么作用?(key的内部原理)
                        
                        1. 虚拟DOM中key的作用:
                                        key是虚拟DOM对象的标识,当数据发生变化时,Vue会根据【新数据】生成【新的虚拟DOM】, 
                                        随后Vue进行【新虚拟DOM】与【旧虚拟DOM】的差异比较,比较规则如下:
                                        
                        2.对比规则:
                                    (1).旧虚拟DOM中找到了与新虚拟DOM相同的key:
                                                ①.若虚拟DOM中内容没变, 直接使用之前的真实DOM!
                                                ②.若虚拟DOM中内容变了, 则生成新的真实DOM,随后替换掉页面中之前的真实DOM。

                                    (2).旧虚拟DOM中未找到与新虚拟DOM相同的key
                                                创建新的真实DOM,随后渲染到到页面。
                                                
                        3. 用index作为key可能会引发的问题:
                                            1. 若对数据进行:逆序添加、逆序删除等破坏顺序操作:
                                                            会产生没有必要的真实DOM更新 ==> 界面效果没问题, 但效率低。

                                            2. 如果结构中还包含输入类的DOM:
                                                            会产生错误DOM更新 ==> 界面有问题。

                        4. 开发中如何选择key?:
                                            1.最好使用每条数据的唯一标识作为key, 比如id、手机号、身份证号、学号等唯一值。
                                            2.如果不存在对数据的逆序添加、逆序删除等破坏顺序操作,仅用于渲染列表用于展示,
                                                使用index作为key是没有问题的。
        -->
        <!-- 准备好一个容器-->
        <div id="root">
            <!-- 遍历数组 -->
            <h2>人员列表(遍历数组)</h2>
            <button @click.once="add">添加一个老刘</button>
            <ul>
                <li v-for="(p,index) of persons" :key="index">
                    {{p.name}}-{{p.age}}
                    <input type="text">
                </li>
            </ul>
        </div>

        <script type="text/javascript">
            Vue.config.productionTip = false
            
            new Vue({
                el:'#root',
                data:{
                    persons:[
                        {id:'001',name:'张三',age:18},
                        {id:'002',name:'李四',age:19},
                        {id:'003',name:'王五',age:20}
                    ]
                },
                methods: {
                    add(){
                        console.log(this);
                        const p = {id:'004',name:'老刘',age:40}
                        this.persons.unshift(p)
                        // this.persons[3] = {id:'004',name:'张三123',age:18};
                    }
                },
            })
        </script>
</html>

三、列表过滤

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8" />
        <title>列表过滤</title>
        <script type="text/javascript" src="../js/vue.js"></script>
    </head>
    <body>
        <!-- 准备好一个容器-->
        <div id="root">
            <h2>人员列表</h2>
            <input type="text" placeholder="请输入名字" v-model="keyWord">
            <ul>
                <li v-for="(p,index) of filPerons" :key="index">
                    {{p.name}}-{{p.age}}-{{p.sex}}
                </li>
            </ul>
        </div>

        <script type="text/javascript">
            Vue.config.productionTip = false
            
            //用watch实现
            //#region 
            /* new Vue({
                el:'#root',
                data:{
                    keyWord:'',
                    persons:[
                        {id:'001',name:'马冬梅',age:19,sex:'女'},
                        {id:'002',name:'周冬雨',age:20,sex:'女'},
                        {id:'003',name:'周杰伦',age:21,sex:'男'},
                        {id:'004',name:'温兆伦',age:22,sex:'男'}
                    ],
                    filPerons:[]
                },
                watch:{
                    keyWord:{
                        immediate:true,
                        handler(val){
                            this.filPerons = this.persons.filter((p)=>{
                                return p.name.indexOf(val) !== -1
                            })
                        }
                    }
                }
            }) */
            //#endregion
            
            //用computed实现
            new Vue({
                el:'#root',
                data:{
                    keyWord:'',
                    persons:[
                        {id:'001',name:'马冬梅',age:19,sex:'女'},
                        {id:'002',name:'周冬雨',age:20,sex:'女'},
                        {id:'003',name:'周杰伦',age:21,sex:'男'},
                        {id:'004',name:'温兆伦',age:22,sex:'男'}
                    ]
                },
                computed:{
                    filPerons(){
                        return this.persons.filter((p)=>{
                            return p.name.indexOf(this.keyWord) !== -1
                        })
                    }
                }
            }) 
        </script>
</html>

四、列表排序

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8" />
        <title>列表排序</title>
        <script type="text/javascript" src="../js/vue.js"></script>
    </head>
    <body>
        <!-- 准备好一个容器-->
        <div id="root">
            <h2>人员列表</h2>
            <input type="text" placeholder="请输入名字" v-model="keyWord">
            <button @click="sortType = 2">年龄升序</button>
            <button @click="sortType = 1">年龄降序</button>
            <button @click="sortType = 0">原顺序</button>
            <ul>
                <li v-for="(p,index) of filPerons" :key="p.id">
                    {{p.name}}-{{p.age}}-{{p.sex}}
                    <input type="text">
                </li>
            </ul>
        </div>

        <script type="text/javascript">
            Vue.config.productionTip = false
            
            new Vue({
                el:'#root',
                data:{
                    keyWord:'',
                    sortType:0, //0原顺序 1降序 2升序
                    persons:[
                        {id:'001',name:'马冬梅',age:30,sex:'女'},
                        {id:'002',name:'周冬雨',age:31,sex:'女'},
                        {id:'003',name:'周杰伦',age:18,sex:'男'},
                        {id:'004',name:'温兆伦',age:19,sex:'男'}
                    ]
                },
                computed:{
                    filPerons(){
                        const arr = this.persons.filter((p)=>{
                            return p.name.indexOf(this.keyWord) !== -1
                        })
                        //判断一下是否需要排序
                        if(this.sortType){
                            arr.sort((p1,p2)=>{
                                return this.sortType === 1 ? p2.age-p1.age : p1.age-p2.age
                            })
                        }
                        return arr
                    }
                }
            }) 

        </script>
</html>

五、更新时的一个问题

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8" />
        <title>更新时的一个问题</title>
        <script type="text/javascript" src="../js/vue.js"></script>
    </head>
    <body>
        <!-- 准备好一个容器-->
        <div id="root">
            <h2>人员列表</h2>
            <button @click="updateMei">更新马冬梅的信息</button>
            <ul>
                <li v-for="(p,index) of persons" :key="p.id">
                    {{p.name}}-{{p.age}}-{{p.sex}}
                </li>
            </ul>
        </div>

        <script type="text/javascript">
            Vue.config.productionTip = false
            
            const vm = new Vue({
                el:'#root',
                data:{
                    persons:[
                        {id:'001',name:'马冬梅',age:30,sex:'女'},
                        {id:'002',name:'周冬雨',age:31,sex:'女'},
                        {id:'003',name:'周杰伦',age:18,sex:'男'},
                        {id:'004',name:'温兆伦',age:19,sex:'男'}
                    ]
                },
                methods: {
                    updateMei(){
                        // this.persons[0].name = '马老师' //奏效
                        // this.persons[0].age = 50 //奏效
                        // this.persons[0].sex = '男' //奏效
                        // this.persons[0] = {id:'001',name:'马老师',age:50,sex:'男'} //不奏效
                        this.persons.splice(0,1,{id:'001',name:'马老师',age:50,sex:'男'})
                    }
                }
            }) 

        </script>
</html>

六、Vue检测数据改变的原理_对象

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8" />
        <title>Vue监测数据改变的原理</title>
        <!-- 引入Vue -->
        <script type="text/javascript" src="../js/vue.js"></script>
    </head>
    <body>
        <!-- 准备好一个容器-->
        <div id="root">
            <h2>学校名称:{{name}}</h2>
            <h2>学校地址:{{address}}</h2>
        </div>
    </body>

    <script type="text/javascript">
        Vue.config.productionTip = false //阻止 vue 在启动时生成生产提示。

        const vm = new Vue({
            el:'#root',
            data:{
                name:'尚硅谷',
                address:'北京',
                student:{
                    name:'tom',
                    age:{
                        rAge:40,
                        sAge:29,
                    },
                    friends:[
                        {name:'jerry',age:35}
                    ]
                }
            }
        })
    </script>
</html>

七、模拟一个数据监测

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8" />
        <title>Document</title>
    </head>
    <body>
        <script type="text/javascript" >

            let data = {
                name:'尚硅谷',
                address:'北京',
            }

            //创建一个监视的实例对象,用于监视data中属性的变化
            const obs = new Observer(data)      
            console.log(obs)    

            //准备一个vm实例对象
            let vm = {}
            vm._data = data = obs

            function Observer(obj){
                //汇总对象中所有的属性形成一个数组
                const keys = Object.keys(obj)
                //遍历
                keys.forEach((k)=>{
                    Object.defineProperty(this,k,{
                        get(){
                            return obj[k]
                        },
                        set(val){
                            console.log(`${k}被改了,我要去解析模板,生成虚拟DOM.....我要开始忙了`)
                            obj[k] = val
                        }
                    })
                })
            }
            
            


        </script>
    </body>
</html>

八、Vue.set的使用

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8" />
        <title>Vue监测数据改变的原理</title>
        <!-- 引入Vue -->
        <script type="text/javascript" src="../js/vue.js"></script>
    </head>
    <body>
        <!-- 准备好一个容器-->
        <div id="root">
            <h1>学校信息</h1>
            <h2>学校名称:{{school.name}}</h2>
            <h2>学校地址:{{school.address}}</h2>
            <h2>校长是:{{school.leader}}</h2>
            <hr/>
            <h1>学生信息</h1>
            <button @click="addSex">添加一个性别属性,默认值是男</button>
            <h2>姓名:{{student.name}}</h2>
            <h2 v-if="student.sex">性别:{{student.sex}}</h2>
            <h2>年龄:真实{{student.age.rAge}},对外{{student.age.sAge}}</h2>
            <h2>朋友们</h2>
            <ul>
                <li v-for="(f,index) in student.friends" :key="index">
                    {{f.name}}--{{f.age}}
                </li>
            </ul>
        </div>
    </body>

    <script type="text/javascript">
        Vue.config.productionTip = false //阻止 vue 在启动时生成生产提示。

        const vm = new Vue({
            el:'#root',
            data:{
                school:{
                    name:'尚硅谷',
                    address:'北京',
                },
                student:{
                    name:'tom',
                    age:{
                        rAge:40,
                        sAge:29,
                    },
                    friends:[
                        {name:'jerry',age:35},
                        {name:'tony',age:36}
                    ]
                }
            },
            methods: {
                addSex(){
                    // Vue.set(this.student,'sex','男')
                    this.$set(this.student,'sex','男')
                }
            }
        })
    </script>
</html>

九、Vue监测数据改变的原理_数组

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8" />
        <title>Vue监测数据改变的原理_数组</title>
        <!-- 引入Vue -->
        <script type="text/javascript" src="../js/vue.js"></script>
    </head>
    <body>
        <!-- 准备好一个容器-->
        <div id="root">
            <h1>学校信息</h1>
            <h2>学校名称:{{school.name}}</h2>
            <h2>学校地址:{{school.address}}</h2>
            <h2>校长是:{{school.leader}}</h2>
            <hr/>
            <h1>学生信息</h1>
            <button @click="addSex">添加一个性别属性,默认值是男</button>
            <h2>姓名:{{student.name}}</h2>
            <h2 v-if="student.sex">性别:{{student.sex}}</h2>
            <h2>年龄:真实{{student.age.rAge}},对外{{student.age.sAge}}</h2>
            <h2>爱好</h2>
            <ul>
                <li v-for="(h,index) in student.hobby" :key="index">
                    {{h}}
                </li>
            </ul>
            <h2>朋友们</h2>
            <ul>
                <li v-for="(f,index) in student.friends" :key="index">
                    {{f.name}}--{{f.age}}
                </li>
            </ul>
        </div>
    </body>

    <script type="text/javascript">
        Vue.config.productionTip = false //阻止 vue 在启动时生成生产提示。

        const vm = new Vue({
            el:'#root',
            data:{
                school:{
                    name:'尚硅谷',
                    address:'北京',
                },
                student:{
                    name:'tom',
                    age:{
                        rAge:40,
                        sAge:29,
                    },
                    hobby:['抽烟','喝酒','烫头'],
                    friends:[
                        {name:'jerry',age:35},
                        {name:'tony',age:36}
                    ]
                }
            },
            methods: {
                addSex(){
                    // Vue.set(this.student,'sex','男')
                    this.$set(this.student,'sex','男')
                }
            }
        })
    </script>
</html>

十、总结Vue数据监测

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8" />
        <title>总结数据监视</title>
        <style>
            button{
                margin-top: 10px;
            }
        </style>
        <!-- 引入Vue -->
        <script type="text/javascript" src="../js/vue.js"></script>
    </head>
    <body>
        <!--
            Vue监视数据的原理:
                1. vue会监视data中所有层次的数据。

                2. 如何监测对象中的数据?
                                通过setter实现监视,且要在new Vue时就传入要监测的数据。
                                    (1).对象中后追加的属性,Vue默认不做响应式处理
                                    (2).如需给后添加的属性做响应式,请使用如下API:
                                                    Vue.set(target,propertyName/index,value) 或 
                                                    vm.$set(target,propertyName/index,value)

                3. 如何监测数组中的数据?
                                    通过包裹数组更新元素的方法实现,本质就是做了两件事:
                                        (1).调用原生对应的方法对数组进行更新。
                                        (2).重新解析模板,进而更新页面。

                4.在Vue修改数组中的某个元素一定要用如下方法:
                            1.使用这些API:push()、pop()、shift()、unshift()、splice()、sort()、reverse()
                            2.Vue.set() 或 vm.$set()
                
                特别注意:Vue.set() 和 vm.$set() 不能给vm 或 vm的根数据对象 添加属性!!!
        -->
        <!-- 准备好一个容器-->
        <div id="root">
            <h1>学生信息</h1>
            <button @click="student.age++">年龄+1岁</button> <br/>
            <button @click="addSex">添加性别属性,默认值:男</button> <br/>
            <button @click="student.sex = '未知' ">修改性别</button> <br/>
            <button @click="addFriend">在列表首位添加一个朋友</button> <br/>
            <button @click="updateFirstFriendName">修改第一个朋友的名字为:张三</button> <br/>
            <button @click="addHobby">添加一个爱好</button> <br/>
            <button @click="updateHobby">修改第一个爱好为:开车</button> <br/>
            <button @click="removeSmoke">过滤掉爱好中的抽烟</button> <br/>
            <h3>姓名:{{student.name}}</h3>
            <h3>年龄:{{student.age}}</h3>
            <h3 v-if="student.sex">性别:{{student.sex}}</h3>
            <h3>爱好:</h3>
            <ul>
                <li v-for="(h,index) in student.hobby" :key="index">
                    {{h}}
                </li>
            </ul>
            <h3>朋友们:</h3>
            <ul>
                <li v-for="(f,index) in student.friends" :key="index">
                    {{f.name}}--{{f.age}}
                </li>
            </ul>
        </div>
    </body>

    <script type="text/javascript">
        Vue.config.productionTip = false //阻止 vue 在启动时生成生产提示。

        const vm = new Vue({
            el:'#root',
            data:{
                student:{
                    name:'tom',
                    age:18,
                    hobby:['抽烟','喝酒','烫头'],
                    friends:[
                        {name:'jerry',age:35},
                        {name:'tony',age:36}
                    ]
                }
            },
            methods: {
                addSex(){
                    // Vue.set(this.student,'sex','男')
                    this.$set(this.student,'sex','男')
                },
                addFriend(){
                    this.student.friends.unshift({name:'jack',age:70})
                },
                updateFirstFriendName(){
                    this.student.friends[0].name = '张三'
                },
                addHobby(){
                    this.student.hobby.push('学习')
                },
                updateHobby(){
                    // this.student.hobby.splice(0,1,'开车')
                    // Vue.set(this.student.hobby,0,'开车')
                    this.$set(this.student.hobby,0,'开车')
                },
                removeSmoke(){
                    this.student.hobby = this.student.hobby.filter((h)=>{
                        return h !== '抽烟'
                    })
                }
            }
        })
    </script>
</html>