1. 箭头函数
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<!--
箭头函数比函数表达式更简洁的一种写法
箭头函数更适用于那些本来需要匿名函数的地方，写法更简单
-->
<script>
// 普通函数
const fn = function () {
console.log('普通函数')
}
fn()
// 箭头函数
const fm = () => {
console.log('箭头函数')
}
fm()
const sum = (x, y) => {
console.log(x + y)
}
sum(1, 2)
</script>
</body>
</html>
2. 箭头函数简写
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<!--
有且仅有一个形参，可以省略小括号不写
函数体只有一句代码，可以省略 { } 和 return
函数体返回对象，需要使用小括号包裹对象
-->
<script>
/* 当箭头函数只有一个参数时，可以省略参数的小括号，
其余个数不能省略（没有参数也需要写小括号） */
const fn1 = (x) => {
console.log(x)
}
fn1(1) // 1
const fn2 = x => {
console.log(x)
}
fn2(2) // 2
/* 当箭头函数的函数体只有一句代码 可以省略函数体大括号，
这句代码就是返回值（可以不用写return） */
const fn3 = (x, y) => {
return x + y
}
console.log(fn3(1, 2)) // 3
const fn4 = (x, y) => x + y
console.log(fn4(1, 2)) // 3
/* 如果返回的是个对象，则需要把对象用小括号包裹 */
const fn5 = () => {
return { age: 18 }
}
console.log(fn5()) // {age: 18}
// 未用小括号，返回值为undefined
const fn6 = () => { age: 18 }
console.log(fn6()) // undefined
// 正确写法
const fn7 = () => ({ age: 18 })
console.log(fn7()) // {age: 18}
</script>
</body>
</html>
3. arguments
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<!--
arguments对象（了解）
arguments 只存在于函数中（但不能在箭头函数中使用）
arguments 的作用是动态获取函数的实参
可以通过for循环依次得到传递过来的实参
-->
<!--
arguments 是一个伪数组，有长度有索引号
但是没有 pop() push() 等数组方法
-->
<script>
// 普通函数
function fn1() {
console.log(arguments)
for (let i = 0; i < arguments.length; i++) {
console.log(arguments[i])
}
}
fn1(1, 4, 6, 7, 23, 35)
// 箭头函数
const fn2 = () => {
console.log(arguments) // 控制台报错 arguments未定义
}
fn2()
</script>
</body>
</html>
4. 剩余参数
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<!--
剩余参数（重点） ：用于获取多余的实参，并形成一个真数组（arguments 是伪数组）
也可以解决形参和实参个数不匹配的问题
-->
<!--
... 是语法符号，置于最末函数形参之前，用于获取多余的实参
借助 ... 获取的剩余实参，是个真数组
普通函数和箭头函数中都可以使用
-->
<script>
// 普通函数
function fn1(x, y, ...other) {
console.log(x, y)
console.log(other)
}
fn1(1, 4, 6, 7, 23, 35)
// 箭头函数
const fn2 = (x, y, ...nums) => {
console.log(x, y)
console.log(nums)
}
fn2(1, 4, 6, 7, 23, 35)
</script>
</body>
</html>
5. 展开运算符
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<!--
展开运算符(…),将一个数组/对象进行展开,不会修改原数组
典型运用场景： 求数组最大值(最小值)、合并数组等
-->
<!--
展开运算符 or 剩余参数
剩余参数：函数参数使用，把多个元素收集起来生成一个真数组 （凝聚）
展开运算符：将数组展开成各个元素（拆散）
-->
<script>
const arr1 = [1, 4, 6, 5, 23, 46, 67, 56]
console.log(...arr1) // 1 4 6 5 23 46 67 56
console.log(Math.max(...arr1)) // 67
console.log(Math.min(...arr1)) // 1
const arr2 = [1, 20, 30, 5, 6]
// 展开运算符 合并数组arr1和arr2
const arr3 = [...arr1, ...arr2]
console.log(arr3) // [1, 4, 6, 5, 23, 46, 67, 56, 1, 20, 30, 5, 6]
// concat 合并数组arr1和arr2
const arr4 = arr1.concat(arr2)
console.log(arr4) // [1, 4, 6, 5, 23, 46, 67, 56, 1, 20, 30, 5, 6]
</script>
</body>
</html>
6. 解构数组
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<!--
解构赋值：
可以将数组中的值或对象的属性取出，赋值给其他变量
把一个事物的结构进行拆解
-->
<script>
// 数组解构 右侧数组的值将被赋值给左侧的变量
const [a, b, c] = [1, 2, 3]
console.log(a) // 1
console.log(b) // 2
console.log(c) // 3
// 交换两个变量
// JS中小括号()和中括号[]开头时，括号前需加分号（或加到上行末尾）
let x = 1
let y = 2
console.log(x, y); // 1 2 (此行末尾需加分号)
[y, x] = [x, y]
console.log(x, y) // 2 1
</script>
</body>
</html>
7. 案例1_数组解构
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<script>
function getValue() {
// 函数返回值可为多个数据 需用[ , ]包裹
return [12, 23]
}
let arr = getValue()
const [a, b] = arr
console.log(a, b) // 12 23
</script>
</body>
</html>
8. 解构数组_变量和值不匹配时
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<!-- 数组解构：变量和值不匹配的情况 -->
<script>
// 1. 变量多值少 多余的变量将被赋值为undefined
const [a1, b1, c1] = [1, 2]
console.log(a1, b1, c1) // 1 2 undefined
// 2. 变量多值少 防止有undefined传递值的情况，可以设置默认值
const [a2, b2, c2 = 0] = [1, 2]
console.log(a2, b2, c2) // 1 2 0
// 3. 变量少值多 多出的值直接忽略
const [a3, b3] = [1, 2, 3, 4, 5]
console.log(a3, b3) // 1 2
// 4. 变量少值多 利用剩余参数(返回为数组)
const [a4, b4, ...nums] = [1, 2, 3, 4, 5]
console.log(a4, b4) // 1 2
console.log(nums) // [3, 4, 5]
// 5. 按需导入，忽略某些值
const [a5, b5, , d5] = [1, 2, 3, 4]
console.log(a5, b5, d5) // 1 2 4
// 6. 多维数组的解构
const [a6, [b6, c6]] = [1, [2, 3]]
console.log(a6, b6, c6) // 1 2 3
</script>
</body>
</html>
9. 解构对象
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<!-- 对象解构赋值：可以将对象的属性取出，赋值给其他变量 -->
<!--
注意：
➢ 对象的属性名一定要和变量名相同
➢ 变量名如果没有和对象属性名相同的则默认是 undefined
➢ 注意解构的变量名不要和外面的变量名冲突,否则报错
-->
<script>
const ym = { name: '杨幂', age: 18 }
const { name, age } = ym
console.log(name, age) // 杨幂 18
// name是JS保留字 起名时尽量避开
// 原名是name，改名后使用旧名name，输出为空
const pig = { pName: '佩奇', pAge: 6 }
const { pName: pigName, pAge } = pig
console.log(pigName, pAge) // 佩奇 6
console.log(pName) // 报错 pName未定义
</script>
</body>
</html>
10. 解构对象数组
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<script>
// 对象数组基本解构方法，后期数组内多个对象时配合遍历解构
const student = [
{ stuName: 'Tom', age: 18 }
]
const [{ stuName, age }] = student
console.log(stuName, age) // Tom 18
</script>
</body>
</html>
11. 解构多级对象
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<script>
const monkey = {
mkName: '孙悟空',
family: {
teacher: '唐僧',
brother1: '猪八戒',
brother2: '沙僧'
}
}
// const { mkName, family } = monkey
// console.log(mkName, family)
// 孙悟空 {teacher: '唐僧', brother1: '猪八戒', brother2: '沙僧'}
const { mkName, family: { brother1, brother2 } } = monkey
console.log(mkName, brother1, brother2) // 孙悟空 猪八戒 沙僧
</script>
</body>
</html>
12. 案例2_多级对象解构
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<script>
const msg = {
"code": 200,
"msg": "获取新闻列表成功",
"data": [
{
"id": 1,
"title": "5G商用自己，三大运用商收入下降",
"count": 58
},
{
"id": 2,
"title": "国际媒体头条速览",
"count": 56
},
{
"id": 3,
"title": "乌克兰和俄罗斯持续冲突",
"count": 1669
},
]
}
// 传参时，形参也可以解构对象
function render1({ data }) {
console.log(data)
}
render1(msg)
// 防止msg里面的data名字混淆，要求渲染函数里面的数据名改为myData
function render2({ data: myData }) {
console.log(myData)
}
render2(msg)
</script>
</body>
</html>
13. 案例3_渲染页面(解构)
<!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>商品渲染</title>
<style>
* {
margin: 0;
padding: 0;
box-sizing: border-box;
}
.list {
width: 990px;
margin: 0 auto;
display: flex;
flex-wrap: wrap;
padding-top: 100px;
}
.item {
width: 240px;
margin-left: 10px;
padding: 20px 30px;
transition: all .5s;
margin-bottom: 20px;
}
.item:nth-child(4n) {
margin-left: 0;
}
.item:hover {
box-shadow: 0px 0px 5px rgba(0, 0, 0, 0.2);
transform: translate3d(0, -4px, 0);
cursor: pointer;
}
.item img {
width: 100%;
}
.item .name {
font-size: 18px;
margin-bottom: 10px;
color: #666;
}
.item .price {
font-size: 22px;
color: firebrick;
}
.item .price::before {
content: "¥";
font-size: 14px;
}
</style>
</head>
<body>
<div class="list">
<!--
<div class="item">
<img src="" alt="">
<p class="name"></p>
<p class="price"></p>
</div>
-->
</div>
<script>
const goodsList = [
{
id: '4001172',
name: '称心如意手摇咖啡磨豆机咖啡豆研磨机',
price: '289.00',
picture: 'https://yanxuan-item.nosdn.127.net/84a59ff9c58a77032564e61f716846d6.jpg',
},
{
id: '4001594',
name: '日式黑陶功夫茶组双侧把茶具礼盒装',
price: '288.00',
picture: 'https://yanxuan-item.nosdn.127.net/3346b7b92f9563c7a7e24c7ead883f18.jpg',
},
{
id: '4001009',
name: '竹制干泡茶盘正方形沥水茶台品茶盘',
price: '109.00',
picture: 'https://yanxuan-item.nosdn.127.net/2d942d6bc94f1e230763e1a5a3b379e1.png',
},
{
id: '4001874',
name: '古法温酒汝瓷酒具套装白酒杯莲花温酒器',
price: '488.00',
picture: 'https://yanxuan-item.nosdn.127.net/44e51622800e4fceb6bee8e616da85fd.png',
},
{
id: '4001649',
name: '大师监制龙泉青瓷茶叶罐',
price: '139.00',
picture: 'https://yanxuan-item.nosdn.127.net/4356c9fc150753775fe56b465314f1eb.png',
},
{
id: '3997185',
name: '与众不同的口感汝瓷白酒杯套组1壶4杯',
price: '108.00',
picture: 'https://yanxuan-item.nosdn.127.net/8e21c794dfd3a4e8573273ddae50bce2.jpg',
},
{
id: '3997403',
name: '手工吹制更厚实白酒杯壶套装6壶6杯',
price: '99.00',
picture: 'https://yanxuan-item.nosdn.127.net/af2371a65f60bce152a61fc22745ff3f.jpg',
},
{
id: '3998274',
name: '德国百年工艺高端水晶玻璃红酒杯2支装',
price: '139.00',
picture: 'https://yanxuan-item.nosdn.127.net/8896b897b3ec6639bbd1134d66b9715c.jpg',
},
]
let str = ''
/* for (let i = 0; i < goodsList.length; i++) {
str += `
<div class="item">
<img src="${goodsList[i].picture}" alt="">
<p class="name">${goodsList[i].name}</p>
<p class="price">${goodsList[i].price}</p>
</div>
`
} */
for (let i = 0; i < goodsList.length; i++) {
// 解构对象
const { name, price, picture } = goodsList[i]
str += `
<div class="item">
<img src="${picture}" alt="">
<p class="name">${name}</p>
<p class="price">${price}</p>
</div>
`
}
document.querySelector('.list').innerHTML = str
</script>
</body>
</html>
14. forEach遍历数组
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<!-- forEach遍历数组元素 不返回数组 -->
<script>
const names = ['Tom', 'Jerry', 'Taylor']
names.forEach((el, index) => {
/*
element是数组元素，简写为el
index是数组元素的索引号
*/
console.log(el, index)
})
/*
Tom 0
Jerry 1
Taylor 2
*/
</script>
</body>
</html>
15. map迭代数组
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<!-- map迭代数组 遍历数组处理数据，并且返回新的数 -->
<!--
map 也称为映射。映射指两个元素的集之间元素相互“对应”的关系。
map重点在于有返回值，forEach没有返回值（undefined）
-->
<script>
const myColor1 = ['红', '绿', '蓝']
console.log(myColor1) // ['红', '绿', '蓝']
const myColor2 = myColor1.map((el, index) => {
return el + '色'
})
console.log(myColor2) // ['红色', '绿色', '蓝色']
</script>
</body>
</html>
16. join拼接数组元素
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<!-- join拼接数组元素 用于把数组中的所有元素连接成一个字符串 -->
<script>
const myColor = ['红色', '绿色', '蓝色']
console.log(myColor.join('')) // 红色绿色蓝色
console.log(myColor.join('--')) // 红色--绿色--蓝色
</script>
</body>
</html>
17. 案例4_渲染页面(map+join)
<!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>商品渲染</title>
<style>
* {
margin: 0;
padding: 0;
box-sizing: border-box;
}
.list {
width: 990px;
margin: 0 auto;
display: flex;
flex-wrap: wrap;
padding-top: 100px;
}
.item {
width: 240px;
margin-left: 10px;
padding: 20px 30px;
transition: all .5s;
margin-bottom: 20px;
}
.item:nth-child(4n) {
margin-left: 0;
}
.item:hover {
box-shadow: 0px 0px 5px rgba(0, 0, 0, 0.2);
transform: translate3d(0, -4px, 0);
cursor: pointer;
}
.item img {
width: 100%;
}
.item .name {
font-size: 18px;
margin-bottom: 10px;
color: #666;
}
.item .price {
font-size: 22px;
color: firebrick;
}
.item .price::before {
content: "¥";
font-size: 14px;
}
</style>
</head>
<body>
<div class="list">
<!--
<div class="item">
<img src="" alt="">
<p class="name"></p>
<p class="price"></p>
</div>
-->
</div>
<script>
const goodsList = [
{
id: '4001172',
name: '称心如意手摇咖啡磨豆机咖啡豆研磨机',
price: '289.00',
picture: 'https://yanxuan-item.nosdn.127.net/84a59ff9c58a77032564e61f716846d6.jpg',
},
{
id: '4001594',
name: '日式黑陶功夫茶组双侧把茶具礼盒装',
price: '288.00',
picture: 'https://yanxuan-item.nosdn.127.net/3346b7b92f9563c7a7e24c7ead883f18.jpg',
},
{
id: '4001009',
name: '竹制干泡茶盘正方形沥水茶台品茶盘',
price: '109.00',
picture: 'https://yanxuan-item.nosdn.127.net/2d942d6bc94f1e230763e1a5a3b379e1.png',
},
{
id: '4001874',
name: '古法温酒汝瓷酒具套装白酒杯莲花温酒器',
price: '488.00',
picture: 'https://yanxuan-item.nosdn.127.net/44e51622800e4fceb6bee8e616da85fd.png',
},
{
id: '4001649',
name: '大师监制龙泉青瓷茶叶罐',
price: '139.00',
picture: 'https://yanxuan-item.nosdn.127.net/4356c9fc150753775fe56b465314f1eb.png',
},
{
id: '3997185',
name: '与众不同的口感汝瓷白酒杯套组1壶4杯',
price: '108.00',
picture: 'https://yanxuan-item.nosdn.127.net/8e21c794dfd3a4e8573273ddae50bce2.jpg',
},
{
id: '3997403',
name: '手工吹制更厚实白酒杯壶套装6壶6杯',
price: '99.00',
picture: 'https://yanxuan-item.nosdn.127.net/af2371a65f60bce152a61fc22745ff3f.jpg',
},
{
id: '3998274',
name: '德国百年工艺高端水晶玻璃红酒杯2支装',
price: '139.00',
picture: 'https://yanxuan-item.nosdn.127.net/8896b897b3ec6639bbd1134d66b9715c.jpg',
},
]
const goodsList1 = goodsList.map((el, index) => {
const { picture, name, price } = el
return `
<div div class="item" >
<img src="${picture}" alt="">
<p class="name">${name}</p>
<p class="price">${price}</p>
</div>
`
})
console.log(goodsList1) // goodsList1现为字符串数组
// console.log(goodsList1.join(''))
document.querySelector('.list').innerHTML = goodsList1.join('')
</script>
</body>
</html>
18. reduce累计器
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<!-- reduce累计器 返回累计处理的结果，经常用于求和等 -->
<!-- arr.reduce(function(上一次值，当前值){}，初始值) -->
<!--
reduce 执行过程:
1.如果有起始值，则把初始值累加到里面;
如果没有起始值， 则上一次值以数组的第一个数组元素的值
2.每一次循环，把返回值给做为 下一次循环的上一次值
3.如果有起始值，则 起始值做为上一次值
-->
<script>
// 1. 数组
const arr = [10, 20, 30]
const sum1 = arr.reduce((prev, current) => {
return prev + current
})
console.log(sum1) // 60
const sum2 = arr.reduce((prev, current) => {
return prev + current
}, 100)
console.log(sum2) // 160
// 2. 对象数组(对象数组.reduce 必须写初始值)
const Peason = [
{
name: '张三',
salary: 10000
}, {
name: '李四',
salary: 15000
}, {
name: '王五',
salary: 20000
}
]
// 未设初始值(错误)
const salary1 = Peason.reduce((prev, current) => {
return prev + current.salary
})
console.log(salary1) // [object Object]1500020000
// 设置初始值
const salary2 = Peason.reduce((prev, current) => {
return prev + current.salary
}, 0)
console.log(salary2) // 45000
</script>
</body>
</html>
19. 案例5_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" />
<title>Document</title>
<style>
* {
margin: 0;
padding: 0;
box-sizing: border-box;
}
.list {
width: 990px;
margin: 100px auto 0;
}
.item {
padding: 15px;
transition: all 0.5s;
display: flex;
border-top: 1px solid #e4e4e4;
}
.item:nth-child(4n) {
margin-left: 0;
}
.item:hover {
cursor: pointer;
background-color: #f5f5f5;
}
.item img {
width: 80px;
height: 80px;
margin-right: 10px;
}
.item .name {
font-size: 18px;
margin-right: 10px;
color: #333;
flex: 2;
}
.item .name .tag {
display: block;
padding: 2px;
font-size: 12px;
color: #999;
}
.item .price,
.item .sub-total {
font-size: 18px;
color: firebrick;
flex: 1;
}
.item .price::before,
.item .sub-total::before,
.amount::before {
content: '¥';
font-size: 12px;
}
.item .spec {
flex: 2;
color: #888;
font-size: 14px;
}
.item .count {
flex: 1;
color: #aaa;
}
.total {
width: 990px;
margin: 0 auto;
display: flex;
justify-content: flex-end;
border-top: 1px solid #e4e4e4;
padding: 20px;
}
.total .amount {
font-size: 18px;
color: firebrick;
font-weight: bold;
margin-right: 50px;
}
</style>
</head>
<body>
<div class="list">
<!-- <div class="item">
<img src="https://yanxuan-item.nosdn.127.net/84a59ff9c58a77032564e61f716846d6.jpg" alt="">
<p class="name">称心如意手摇咖啡磨豆机咖啡豆研磨机 </p>
<p class="price">289.90</p>
<p class="count">x2</p>
<p class="sub-total">579.80</p>
</div> -->
</div>
<div class="total">
<div>
合计：
<span class="amount">1000.00</span>
</div>
</div>
<script>
const goodsList = [
{
id: '4001172',
name: '称心如意手摇咖啡磨豆机咖啡豆研磨机',
price: 289.9,
picture:
'https://yanxuan-item.nosdn.127.net/84a59ff9c58a77032564e61f716846d6.jpg',
count: 2,
spec: { color: '白色' },
},
{
id: '4001009',
name: '竹制干泡茶盘正方形沥水茶台品茶盘',
price: 109.8,
picture:
'https://yanxuan-item.nosdn.127.net/2d942d6bc94f1e230763e1a5a3b379e1.png',
count: 3,
spec: { size: '40cm*40cm', color: '黑色' },
},
{
id: '4001874',
name: '古法温酒汝瓷酒具套装白酒杯莲花温酒器',
price: 488,
picture:
'https://yanxuan-item.nosdn.127.net/44e51622800e4fceb6bee8e616da85fd.png',
count: 1,
spec: { color: '青色', sum: '一大四小' },
gift: '500g茶叶,羽毛球',
},
{
id: '4001649',
name: '大师监制龙泉青瓷茶叶罐',
price: 139,
picture:
'https://yanxuan-item.nosdn.127.net/4356c9fc150753775fe56b465314f1eb.png',
count: 2,
spec: { size: '小号', color: '紫色' },
gift: '50g茶叶,清洗球',
},
]
// 数字转字符串 toFixed(保留小数位数) 默认不保留 四舍五入
let str = goodsList.map((el, index) => {
const { name, price, picture, count } = el
return `
<div class="item">
<img src="${picture}" alt="">
<p class="name">${name}</p>
<p class="price">${price.toFixed(2)}</p>
<p class="count">x${count}</p>
<p class="sub-total">${(price * count).toFixed(2)}</p>
</div>
`
}).join('')
document.querySelector('.list').innerHTML = str
let amount = goodsList.reduce((prev, current) => {
return prev + current.count * current.price
}, 0)
document.querySelector('.amount').innerHTML = amount.toFixed(2)
</script>
</body>
</html>
20. 作业
20.1 确认订单页面
<!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>
<style>
* {
margin: 0;
padding: 0;
box-sizing: border-box;
}
a {
text-decoration: none;
}
.xtx-cart-page .container {
width: 1200px;
margin: 50px auto;
border: 3px solid #ccc;
}
.xtx-cart-page h3 {
text-align: center;
font-size: 30px;
margin: 20px 0;
}
.tc {
text-align: center;
}
.tc .xtx-numbox {
margin: 0 auto;
width: 120px;
}
.red {
color: #db2828;
}
.green {
color: #32aa66;
}
.f16 {
font-size: 16px;
}
.goods {
display: flex;
align-items: center;
}
.goods img {
width: 100px;
height: 100px;
}
.goods>div {
width: 280px;
font-size: 16px;
padding-left: 10px;
}
.goods>div .attr {
font-size: 14px;
color: #999;
}
.action {
display: flex;
background: #fff;
margin-top: 20px;
height: 80px;
align-items: center;
font-size: 16px;
justify-content: space-between;
padding: 0 30px;
}
.action .xtx-checkbox {
color: #999;
}
.action .batch a {
margin-left: 20px;
}
.action .red {
font-size: 18px;
margin-right: 20px;
font-weight: bold;
}
.tit {
color: #666;
font-size: 16px;
font-weight: normal;
line-height: 50px;
}
.xtx-cart-page .cart {
background: #fff;
color: #666;
}
.xtx-cart-page .cart table {
border-spacing: 0;
border-collapse: collapse;
line-height: 24px;
}
.xtx-cart-page .cart table th,
.xtx-cart-page .cart table td {
padding: 10px;
border-bottom: 1px solid #f5f5f5;
}
.xtx-cart-page .cart table th:first-child,
.xtx-cart-page .cart table td:first-child {
text-align: left;
padding-left: 30px;
color: #999;
}
.xtx-cart-page .cart table th {
font-size: 16px;
font-weight: normal;
line-height: 50px;
}
.box {
width: 1200px;
margin: 0 auto;
}
.box p {
height: 30px;
line-height: 30px;
}
</style>
</head>
<body>
<!-- ---------------------- 题目区域 --------------------------- -->
<div class="box">
<p>题目说明：</p>
<p>1. 基于 arr（代码中已准备） 渲染下面购物车列表</p>
<p>2. 基于 arr 计算 底部总价 和 总数量</p>
<p>3. 实现 删除功能</p>
</div>
<!-- ---------------------- 代码区域 ---------------------------- -->
<div class="xtx-cart-page">
<div class="container">
<div class="cart">
<h3>确认订单</h3>
<table>
<thead>
<tr>
<th width="120">序号</th>
<th width="400">商品信息</th>
<th width="220">单价</th>
<th width="180">数量</th>
<th width="180">小计</th>
<th width="140">操作</th>
</tr>
</thead>
<!-- 商品列表 -->
<tbody>
<tr>
<td>1</td>
<td>
<div class="goods">
<a href="#/"><img src="https://yanxuan-item.nosdn.127.net/6aaff130c1d97c60f9931e00734bbad6.png"
alt=""></a>
<div>
<p class="name ellipsis">
共享品茶乐趣公道杯闻香杯手工吹制
</p>
<p class="attr">规格：公道杯230ml/手工吹制</p>
</div>
</div>
</td>
<td class="tc">
<p>¥89.00</p>
</td>
<td class="tc">10</td>
<td class="tc">
<p class="f16 red">¥890.00</p>
</td>
<td class="tc">
<p><a class="green" href="javascript:;" onclick="del()">删除</a></p>
</td>
</tr>
</tbody>
</table>
</div>
<!-- 操作栏 -->
<div class="action">
<div class="batch"></div>
<div class="total">
共 9 件商品，商品合计：
<span class="red">¥1800</span>
</div>
</div>
</div>
</div>
<script>
const arr = [
{
id: '1652038',
attrsText: '规格：公道杯230ml/手工吹制',
name: '共享品茶乐趣公道杯闻香杯手工吹制',
price: '89.00',
picture:
'https://yanxuan-item.nosdn.127.net/6aaff130c1d97c60f9931e00734bbad6.png',
count: 10,
},
{
id: '1096001',
attrsText: '规格：不锈钢除味皂',
name: '祛味除腥神器，不锈钢除味皂',
price: '9.90',
picture:
'https://yanxuan-item.nosdn.127.net/b38f9ac476ec494235f4aa80fc8e198c.png',
count: 1,
},
{
id: '3446012',
attrsText: '颜色：芭比粉-老款',
name: '一锅包揽煎烤蒸煮日本爱丽思多功能料理锅',
price: '299.00',
picture:
'https://yanxuan-item.nosdn.127.net/667dbc276e46e31b5a00869b9b1b8ef3.png',
count: 2,
},
{
id: '1652037',
attrsText: '规格：黑白对杯',
name: '茶水分离杯耐热隔热玻璃杯',
price: '188.00',
picture:
'https://yanxuan-item.nosdn.127.net/a09de222ed32efa8ffe359b1d5780574.jpg',
count: 5,
},
{
id: '3504000',
name: '儿童防污/防蚊T恤110cm',
attrsText: '颜色：白色草莓（防污） 尺码：160cm',
price: '89.00',
picture:
'https://yanxuan-item.nosdn.127.net/f899c55f36cb74232abb349234d9e676.png',
count: 4,
},
]
function render() {
const tbody = document.querySelector('.cart tbody')
const action = document.querySelector('.action')
// 利用map+join渲染数据到页面上
const str = arr.map((el, index) => {
const { name, attrsText, price, picture, count } = el
return `
<tr>
<td>${index + 1}</td>
<td>
<div class="goods">
<a href="#/"><img src="${picture}"
alt=""></a>
<div>
<p class="name ellipsis">
${name}}
</p>
<p class="attr">${attrsText}</p>
</div>
</div>
</td>
<td class="tc">
<p>¥${price}</p>
</td>
<td class="tc">${count}</td>
<td class="tc">
<p class="f16 red">¥${(price * count).toFixed(2)}</p>
</td>
<td class="tc">
<p><a class="green" href="javascript:;" onclick="del(${index})">删除</a></p>
</td>
</tr>
`
}).join('')
// document.querySelector('.cart tbody').innerHTML = str
tbody.innerHTML = str
// 利用reduce来求和
// 箭头函数 省略大括号和return
const totalCount = arr.reduce((prev, current) => prev + current.count, 0)
const totalPrice = arr.reduce((prev, current) => prev + current.count * current.price, 0)
/* const totalCount = arr.reduce((prev, current) => {
return prev + current.count
}, 0)
const totalPrice = arr.reduce((prev, current) => {
return prev + current.count * current.price
}, 0).toFixed(2) */
action.innerHTML = `
<div class="batch"></div>
<div class="total">
共 ${totalCount} 件商品，商品合计：
<span class="red">¥${totalPrice.toFixed(2)}</span>
</div>
`
/* document.querySelector('.total').innerHTML = `
共 ${totalCount} 件商品，商品合计：
<span class="red">¥${totalPrice.toFixed(2)}</span>
` */
}
render()
// 利用splice来删除数据
function del(index) {
arr.splice(index, 1)
render()
}
</script>
</body>
</html>
20.2 水果列表_二次开发题
<!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">
<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 class="tr active">
<div class="td"><input type="checkbox" checked /></div>
<div class="td"><img src="./img/火龙果.png" alt="" /></div>
<div class="td">6</div>
<div class="td">
<div class="my-input-number">
<button class="decrease"> - </button>
<span class="my-input__inner">2</span>
<button class="increase"> + </button>
</div>
</div>
<div class="td">12</div>
<div class="td"><a href="javascript:;" onclick="del(0)">删除</a></div>
</div>
<!-- 需要渲染的列表 核心代码区域 -->
<div class="tr">
<div class="td"><input type="checkbox" /></div>
<div class="td"><img src="./img/荔枝.png" alt="" /></div>
<div class="td">7</div>
<div class="td">
<div class="my-input-number">
<button disabled class="decrease"> - </button>
<span class="my-input__inner">1</span>
<button class="increase"> + </button>
</div>
</div>
<div class="td">14</div>
<div class="td"><a href="javascript:;" onclick="del(0)">删除</a></div>
</div>
</div>
</div>
<!-- 底部 -->
<div class="bottom">
<!-- 全选 -->
<label class="check-all">
<input type="checkbox" />
全选
</label>
<div class="right-box">
<!-- 所有商品总价 -->
<span class="price-box">总价 : ¥ <span class="price">24</span></span>
<!-- 结算按钮 -->
<button class="pay">结算( 6 )</button>
</div>
</div>
</div>
<!-- 空车 -->
<div class="empty">🛒空空如也</div>
</div>
<script>
const fruit = [
{
icon: './img/火龙果.png',
num: 2,
price: 6,
},
{
icon: './img/荔枝.png',
num: 7,
price: 20,
},
{
icon: './img/榴莲.png',
num: 3,
price: 40,
},
{
icon: './img/鸭梨.png',
num: 10,
price: 3,
},
{
icon: './img/樱桃.png',
num: 20,
price: 34,
}
]
function render() {
// 渲染购物车列表数据，使用map+join配合实现
/* const str = fruit.map((el, index) => {
const { icon, num, price } = el */
const str = fruit.map(({ icon, num, price }, index) => {
return `
<div class="tr">
<div class="td"><input type="checkbox" /></div>
<div class="td"><img src="${icon}" alt="" /></div>
<div class="td">${price}</div>
<div class="td">
<div class="my-input-number">
<button disabled class="decrease"> - </button>
<span class="my-input__inner">${num}</span>
<button class="increase"> + </button>
</div>
</div>
<div class="td">${(price * num)}</div>
<div class="td"><a href="javascript:;" onclick="del(${index})">删除</a></div>
</div>
`
}).join('')
document.querySelector('.tbody').innerHTML = str
// 求和功能用reduce实现
/* const Price = fruit.reduce((prev, current) => {
return prev + current.price * current.num
}, 0)
const Count = fruit.reduce((prev, current) => {
return prev + current.num
}, 0) */
const Price = fruit.reduce((prev, current) => prev + current.price * current.num, 0)
const Count = fruit.reduce((prev, current) => prev + current.num, 0)
document.querySelector('.right-box').innerHTML = `
<span class="price-box">总价 : ¥ <span class="price">${Price}</span></span>
<button class="pay">结算( ${Count} )</button>
`
}
render()
function del(index) {
fruit.splice(index, 1)
render()
}
</script>
</body>
</html>
20.3 暂时性锁区
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<!-- 暂时性死区 -->
<!-- 在代码块内，使用let命令声明变量之前，该变量都是不可用的。
这在语法上，称为“暂时性死区” -->
<script>
let tmp = 123
if (true) {
tmp = 'abc'
console.log(tmp) // 报错：在初始化之前无法访问'tmp'
let tmp
}
</script>
</body>
</html>
扫一扫
1498
被折叠的 条评论
为什么被折叠?
到【灌水乐园】发言
