Vue（3）

一.生命周期及其四个阶段

Vue生命周期：一个Vue实例从创建到销毁的整个过程
生命周期四个阶段：①创建②挂载③更新④销毁

<body><div id="app"><h3>{{ title }}</h3><div><button @click="count--">-</button><span>{{ count }}</span><button @click="count++">+</button></div></div><script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script><script>const app = new Vue({el: '#app',data: {count: 100,title: '计数器'},// 1. 创建阶段（准备数据）beforeCreate () {console.log('beforeCreate 响应式数据准备好之前', this.count)},created () {console.log('created 响应式数据准备好之后', this.count)// this.数据名 = 请求回来的数据// 可以开始发送初始化渲染的请求了},// 2. 挂载阶段（渲染模板）beforeMount () {console.log('beforeMount 模板渲染之前', document.querySelector('h3').innerHTML)},mounted () {console.log('mounted 模板渲染之后', document.querySelector('h3').innerHTML)// 可以开始操作dom了},// 3. 更新阶段(修改数据 → 更新视图)beforeUpdate () {console.log('beforeUpdate 数据修改了，视图还没更新', document.querySelector('span').innerHTML)},updated () {console.log('updated 数据修改了，视图已经更新', document.querySelector('span').innerHTML)},// 4. 卸载阶段beforeDestroy () {console.log('beforeDestroy, 卸载前')console.log('清除掉一些Vue以外的资源占用，定时器，延时器...')},destroyed () {console.log('destroyed，卸载后')}})</script>
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二.created应用

created：响应式数据准备好了，可以开始发送初始化渲染请求

<head><style>* {margin: 0;padding: 0;list-style: none;}.news {display: flex;height: 120px;width: 600px;margin: 0 auto;padding: 20px 0;cursor: pointer;}.news .left {flex: 1;display: flex;flex-direction: column;justify-content: space-between;padding-right: 10px;}.news .left .title {font-size: 20px;}.news .left .info {color: #999999;}.news .left .info span {margin-right: 20px;}.news .right {width: 160px;height: 120px;}.news .right img {width: 100%;height: 100%;object-fit: cover;}</style>
</head>
<body><div id="app"><ul><li v-for="(item, index) in list" :key="item.id" class="news"><div class="left"><div class="title">{{ item.title }}</div><div class="info"><span>{{ item.source }}</span><span>{{ item.time }}</span></div></div><div class="right"><img :src="item.img" alt=""></div></li></ul></div><script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script><script src="https://cdn.jsdelivr.net/npm/axios/dist/axios.min.js"></script><script>// 接口地址：http://hmajax.itheima.net/api/news// 请求方式：getconst app = new Vue({el: '#app',data: {list: []},async created () {// 1. 发送请求获取数据const res = await axios.get('http://hmajax.itheima.net/api/news')// 2. 更新到 list 中，用于页面渲染 v-forthis.list = res.data.data}})</script>
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三.小黑的记账清单

  <head><!-- CSS only --><linkrel="stylesheet"href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css"/><style>.red {color: red!important;}.search {width: 300px;margin: 20px 0;}.my-form {display: flex;margin: 20px 0;}.my-form input {flex: 1;margin-right: 20px;}.table > :not(:first-child) {border-top: none;}.contain {display: flex;padding: 10px;}.list-box {flex: 1;padding: 0 30px;}.list-box  a {text-decoration: none;}.echarts-box {width: 600px;height: 400px;padding: 30px;margin: 0 auto;border: 1px solid #ccc;}tfoot {font-weight: bold;}@media screen and (max-width: 1000px) {.contain {flex-wrap: wrap;}.list-box {width: 100%;}.echarts-box {margin-top: 30px;}}</style></head><body><div id="app"><div class="contain"><!-- 左侧列表 --><div class="list-box"><!-- 添加资产 --><form class="my-form"><input v-model.trim="name" type="text" class="form-control" placeholder="消费名称" /><input v-model.number="price" type="text" class="form-control" placeholder="消费价格" /><button @click="add" type="button" class="btn btn-primary">添加账单</button></form><table class="table table-hover"><thead><tr><th>编号</th><th>消费名称</th><th>消费价格</th><th>操作</th></tr></thead><tbody><tr v-for="(item, index) in list" :key="item.id"><td>{{ index + 1 }}</td><td>{{ item.name }}</td><td :class="{ red: item.price > 500 }">{{ item.price.toFixed(2) }}</td><td><a @click="del(item.id)" href="javascript:;">删除</a></td></tr></tbody><tfoot><tr><td colspan="4">消费总计： {{ totalPrice.toFixed(2) }}</td></tr></tfoot></table></div><!-- 右侧图表 --><div class="echarts-box" id="main"></div></div></div><script src="https://cdn.jsdelivr.net/npm/echarts@5.4.0/dist/echarts.min.js"></script><script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script><script src="https://cdn.jsdelivr.net/npm/axios/dist/axios.min.js"></script><script>/*** 接口文档地址：* https://www.apifox.cn/apidoc/shared-24459455-ebb1-4fdc-8df8-0aff8dc317a8/api-53371058* * 功能需求：* 1. 基本渲染*    (1) 立刻发送请求获取数据 created*    (2) 拿到数据，存到data的响应式数据中*    (3) 结合数据，进行渲染 v-for*    (4) 消费统计 => 计算属性* 2. 添加功能*    (1) 收集表单数据 v-model*    (2) 给添加按钮注册点击事件，发送添加请求*    (3) 需要重新渲染* 3. 删除功能*    (1) 注册点击事件，传参传 id*    (2) 根据 id 发送删除请求*    (3) 需要重新渲染* 4. 饼图渲染*    (1) 初始化一个饼图 echarts.init(dom)  mounted钩子实现*    (2) 根据数据实时更新饼图 echarts.setOption({ ... })*/const app = new Vue({el: '#app',data: {list: [],name: '',price: ''},computed: {totalPrice () {return this.list.reduce((sum, item) => sum + item.price, 0)}},created () {// const res = await axios.get('https://applet-base-api-t.itheima.net/bill', {//   params: {//     creator: '小黑'//   }// })// this.list = res.data.datathis.getList()},mounted () {this.myChart = echarts.init(document.querySelector('#main'))this.myChart.setOption({// 大标题title: {text: '消费账单列表',left: 'center'},// 提示框tooltip: {trigger: 'item'},// 图例legend: {orient: 'vertical',left: 'left'},// 数据项series: [{name: '消费账单',type: 'pie',radius: '50%', // 半径data: [// { value: 1048, name: '球鞋' },// { value: 735, name: '防晒霜' }],emphasis: {itemStyle: {shadowBlur: 10,shadowOffsetX: 0,shadowColor: 'rgba(0, 0, 0, 0.5)'}}}]})},methods: {async getList () {const res = await axios.get('https://applet-base-api-t.itheima.net/bill', {params: {creator: '小黑'}})this.list = res.data.data// 更新图表this.myChart.setOption({// 数据项series: [{// data: [//   { value: 1048, name: '球鞋' },//   { value: 735, name: '防晒霜' }// ]data: this.list.map(item => ({ value: item.price, name: item.name}))}]})},async add () {if (!this.name) {alert('请输入消费名称')return}if (typeof this.price !== 'number') {alert('请输入正确的消费价格')return}// 发送添加请求const res = await axios.post('https://applet-base-api-t.itheima.net/bill', {creator: '小黑',name: this.name,price: this.price})// 重新渲染一次this.getList()this.name = ''this.price = ''},async del (id) {// 根据 id 发送删除请求const res = await axios.delete(`https://applet-base-api-t.itheima.net/bill/${id}`)// 重新渲染this.getList()}}})</script></body>