Vue Day2【综合案例】成绩案例&水果购物车
一、成绩案例
<!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" />
<link rel="stylesheet" href="./styles/index.css" />
<title>Document</title>
</head>
<body>
<div id="app" class="score-case">
<div class="table">
<table>
<thead>
<tr>
<th>编号</th>
<th>科目</th>
<th>成绩</th>
<th>操作</th>
</tr>
</thead>
<tbody v-if="list.length > 0">
<tr v-for="item in list" :key="item.id">
<td>{{ index + 1 }}</td>
<td>{{ item.subject }}</td>
<td :class="{red: item.score < 60}">{{ item.score }}</td>
<td><a href="#" @click.prevent="del(item.id)">删除</a></td>
</tr>
</tbody>
<tbody v-else>
<tr>
<td colspan="5">
<span class="none">暂无数据</span>
</td>
</tr>
</tbody>
<tfoot>
<tr>
<td colspan="5">
<span>总分：{{ total }}</span>
<span style="margin-left: 50px">平均分：{{ total/list.length || 0 }}</span>
</td>
</tr>
</tfoot>
</table>
</div>
<div class="form">
<div class="form-item">
<div class="label">科目：</div>
<div class="input">
<input v-model.trim="subject" type="text" placeholder="请输入科目" />
</div>
</div>
<div class="form-item">
<div class="label">分数：</div>
<div class="input">
<input v-model.number="score" type="text" placeholder="请输入分数" />
</div>
</div>
<div class="form-item">
<div class="label"></div>
<div class="input">
<button @click="ad" class="submit">添加</button>
</div>
</div>
</div>
</div>
<script src="../vue.js"></script>
<!-- 需求说明：
1. 渲染功能
2. 删除功能
3. 添加功能
v-model修饰符
4. 统计总分，求平均分 -->
<script>
const app = new Vue({
el: '#app',
data: {
list: [
{ id: 1, subject: '语文', score: 20 },
{ id: 7, subject: '数学', score: 99 },
{ id: 12, subject: '英语', score: 70 },
],
subject: '',
score: ''
},
computed: {
total() {
return this.list.reduce((sum, item) => sum + item.score, 0)
}
},
// 请先判断 是否有数据；输入的分数是否为数字
// 清空输入框
methods: {
del(id) {
this.list = this.list.filter(item => item.id !== id)
},
ad() {
if (this.subject === '' || this.score.trim === '') {
alert("请输入科目/成绩")
return
}
if (typeof this.score !== 'number') {
alert("请输入正确的成绩")
return
}
this.list.unshift({ id: +new Date, subject: this.subject, score: this.score })
this.subject = ''
this.score = ''
}
}
})
</script>
</body>
</html>
二、水果购物车
<!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" />
<link rel="stylesheet" href="./css/inputnumber.css" />
<link rel="stylesheet" href="./css/index.css" />
<title>购物车</title>
</head>
<body>
<div class="app-container" id="app">
<!-- 顶部banner -->
<div class="banner-box"><img src="./img/fruit.jpg" alt="" /></div>
<!-- 面包屑 -->
<div class="breadcrumb">
<span>🏠</span>
/
<span>购物车</span>
</div>
<!-- 购物车主体 -->
<div class="main" v-if="fruitList.length > 0">
<div class="table">
<!-- 头部 -->
<div class="thead">
<div class="tr">
<div class="th">选中</div>
<div class="th th-pic">图片</div>
<div class="th">单价</div>
<div class="th num-th">个数</div>
<div class="th">小计</div>
<div class="th">操作</div>
</div>
</div>
<!-- 身体 -->
<div class="tbody">
<div v-for="(item, index) in fruitList" :key="item.id" class="tr" :class="{ active: item.isChecked }">
<div class="td"><input type="checkbox" v-model="item.isChecked" /></div>
<div class="td"><img :src="item.icon" alt="" /></div>
<div class="td">{{ item.price }}</div>
<div class="td">
<div class="my-input-number">
<button :disabled="item.num <= 1" class="decrease" @click="sub(item.id)"> - </button>
<span class="my-input__inner">{{ item.num }}</span>
<button class="increase" @click="add(item.id)"> + </button>
</div>
</div>
<div class="td">{{ item.price * item.num }}</div>
<div class="td"><button @click="del(item.id)">删除</button></div>
</div>
</div>
</div>
<!-- 底部 -->
<div class="bottom">
<!-- 全选 -->
<label class="check-all">
<input type="checkbox" v-model="isAll" />
全选
</label>
<div class="right-box">
<!-- 所有商品总价 -->
<span class="price-box">总价 : ¥ <span class="price">{{ totalPrice }}</span></span>
<!-- 结算按钮 -->
<button class="pay">结算( {{ totalCount }} )</button>
</div>
</div>
</div>
<!-- 空车 -->
<div class="empty" v-else>🛒空空如也</div>
</div>
<script src="../vue.js"></script>
<script>
// 1. 渲染功能：v-if/v-else v-for :class
// 2. 删除功能：点击传参 filter 过滤覆盖原数组
// 3. 修改个数：点击传参 find 找对象 disabled 小于等于1时禁用'-'
// 4. 全选反选：计算属性computed 完整写法 get/set
// 5. 统计选中的总价和总数量：计算属性computed reduce条件求和
// 6. 持久化到本地：watch监视，localStorage，JSON.stringify，JSON.parse
const defaultArr = [ // 初始的水果列表
{
id: 1,
icon: './img/火龙果.png',
isChecked: true,
num: 2,
price: 6,
},
{
id: 2,
icon: './img/荔枝.png',
isChecked: false,
num: 7,
price: 20,
},
{
id: 3,
icon: './img/榴莲.png',
isChecked: false,
num: 3,
price: 40,
},
{
id: 4,
icon: './img/鸭梨.png',
isChecked: true,
num: 10,
price: 3,
},
{
id: 5,
icon: './img/樱桃.png',
isChecked: false,
num: 20,
price: 34,
},
]
const app = new Vue({
el: '#app',
data: {
// 水果列表 优先将本地的进行渲染，否则设置一个空数组 getItem
// fruitList: JSON.parse(localStorage.getItem('list')) || []
fruitList: JSON.parse(localStorage.getItem('list')) || defaultArr
},
// 6. 持久化到本地：watch监视，localStorage，JSON.stringify，JSON.parse
watch: {
fruitList: {
deep: true,
handler(newValue) {
// 需要将变化后的 newValue 存入本地（转JSON） setItem
localStorage.setItem('list', JSON.stringify(newValue))
}
}
},
methods: {
// 2. 删除功能：点击传参 filter 过滤覆盖原数组
del(id) {
this.fruitList = this.fruitList.filter(item => item.id !== id)
},
// 3. 修改个数：点击传参 find 找对象 disabled 小于等于1时禁用'-'
add(id) {
// 1. 根据id找到数组中的对应项 → find
const fruit = this.fruitList.find(item => item.id === id)
// 2. 操作num数量
fruit.num++
},
sub(id) {
// 1. 根据id找到数组中的对应项 → find
const fruit = this.fruitList.find(item => item.id === id)
// 2. 操作num数量
fruit.num--
}
},
computed: {
// 默认计算属性：只能获取不能设置，所以要写完整属性 - get + set
// 4. 全选反选：计算属性computed 完整写法 get/set
isAll: {
get() {
// 必须所有的小选框都选中，全选按钮才选中 → every
return this.fruitList.every(item => item.isChecked)
},
set(value) {
// 基于拿到的布尔值，要让所有的小选框 同步状态
this.fruitList.forEach(item => item.isChecked = value)
}
},
// 5. 统计选中的总价和总数量：计算属性computed reduce条件求和
totalCount() {
return this.fruitList.reduce((sum, item) => item.isChecked ? sum + item.num : sum, 0)
},
totalPrice() {
return this.fruitList.reduce((sum, item) => item.isChecked ? sum + item.num * item.price : sum, 0)
}
}
})
</script>
</body>
</html>
在 JavaScript 中，空数组 [] 在布尔上下文中会被视为 true。这是因为空数组是一个对象，而对象在布尔转换时始终为 true。
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