前端学习——JS进阶 (Day2)

深入对象

创建对象三种方式

在这里插入图片描述

构造函数

在这里插入图片描述

小练习

<!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>
</head>

<body>
  <script>
    // 创建一个猪 构造函数 
    function Pig(uname, age) {
      this.uname = uname
      this.age = age
    }

    // console.log(new Pig('佩奇', 6))
    // console.log(new Pig('乔治', 3))
    const p = new Pig('佩奇', 6)
    console.log(p)

    //  const pepa = { uname: '佩奇', age: 6 }

    // const obj = new Object()

    function Goods(name, price, count) {
      this.name = name
      this.price = price
      this.count = count
      this.sayhi = function () { }
    }
    const mi = new Goods('小米', 1999, 20)
    console.log(mi)
    const hw = new Goods('华为', 3999, 59)
    console.log(hw)
    console.log(mi === hw)
    mi.name = 'vivo'
    console.log(mi)
    console.log(hw)
    // const date = new Date('2022-4-8')
    // console.log(date)

    // 静态成员 
    Goods.num = 10
    console.log(Goods.num)
    Goods.sayhi = function () { }
  </script>
</body>

</html>

实例化执行过程

在这里插入图片描述

实例成员&静态成员

在这里插入图片描述

内置构造函数

在这里插入图片描述

Object

在这里插入图片描述

<!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>
</head>

<body>
  <script>
    const o = { uname: 'pink', age: 18 }
    // 1.获得所有的属性名
    console.log(Object.keys(o))  //返回数组['uname', 'age']
    // 2. 获得所有的属性值
    console.log(Object.values(o))  //  ['pink', 18]
    // 3. 对象的拷贝
    // const oo = {}
    // Object.assign(oo, o)
    // console.log(oo)
    Object.assign(o, { gender: '女' })
    console.log(o)
  </script>
</body>

</html>

在这里插入图片描述

Array

在这里插入图片描述

<!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>
</head>

<body>
  <script>
    const arr = [1,5,8]

    // 没有初始值
    const total = arr.reduce(function(prev,current){
      return prev+current
    })
    console.log(total)

    // 有初始值
    const total1 = arr.reduce(function(prev,current){
      return prev+current
    },10)
    console.log(total1)
  </script>
</body>

</html>

在这里插入图片描述
练习

<!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>
</head>

<body>
  <script>
    const arr = [{
      name: '张三',
      salary: 10000
    }, {
      name: '李四',
      salary: 10000
    }, {
      name: '王五',
      salary: 10000
    },
    ]

    const total = arr.reduce((prev,current)=>{
      return prev+current.salary*1.3
    },0)
    console.log(total)
  </script>
</body>

</html>

![在这里插入图片描述](https://img-blog.csdnimg.cn/cb937160e98749bb89f4a1bdccb70855.p

<!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>
</head>

<body>
  <script>
    // const arr = ['red', 'blue', 'green']
    // const re = arr.find(function (item) {
    //   return item === 'blue'
    // })
    // console.log(re)

    const arr = [
      {
        name: '小米',
        price: 1999
      },
      {
        name: '华为',
        price: 3999
      },
    ]
    // 找小米 这个对象，并且返回这个对象
    // const mi = arr.find(function (item) {
    //   // console.log(item)  //
    //   // console.log(item.name)  //
    //   console.log(111)
    //   return item.name === '华为'
    // })
    // 1. find 查找
    // const mi = arr.find(item => item.name === '小米')
    // console.log(mi)
    // 2. every 每一个是否都符合条件，如果都符合返回 true ，否则返回false
    const arr1 = [10, 20, 30]
    const flag = arr1.every(item => item >= 20)
    console.log(flag)
  </script>
</body>

</html>

练习
在这里插入图片描述

<!DOCTYPE html>
<html lang="zh-CN">
<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>
</head>
<body>
  <div></div>
  <script>
    const spec = {size:'40cm*40cm',color:'黑色'}
    // console.log(Object.values(spec))
    document.querySelector('div').innerHTML = Object.values(spec).join('/')
  </script>
</body>
</html>

在这里插入图片描述

<!DOCTYPE html>
<html lang="zh-CN">
<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>
</head>
<body>
  <ul>
    <li>1</li>
    <li>2</li>
    <li>3</li>
  </ul>
  <script>
   const lis = document.querySelectorAll('ul li')
  //  console.log(lis)
  const liss = Array.from(lis)
  console.log(liss)
  liss.pop()
  console.log(liss)
  </script>
</body>
</html>

在这里插入图片描述

String

在这里插入图片描述

<!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>
</head>

<body>
  <script>
    //1. split 把字符串 转换为 数组  和 join() 相反
    // const str = 'pink,red'
    // const arr = str.split(',')
    // console.log(arr)
    // const str1 = '2022-4-8'
    // const arr1 = str1.split('-')
    // console.log(arr1)
    // 2. 字符串的截取   substring(开始的索引号[， 结束的索引号])
    // 2.1 如果省略 结束的索引号，默认取到最后
    // 2.2 结束的索引号不包含想要截取的部分
    // const str = '今天又要做核酸了'
    // console.log(str.substring(5, 7))
    // 3. startsWith 判断是不是以某个字符开头
    // const str = 'pink老师上课中'
    // console.log(str.startsWith('pink'))
    // 4. includes 判断某个字符是不是包含在一个字符串里面
    const str = '我是pink老师'
    console.log(str.includes('pink')) // true
  </script>
</body>

</html>

练习
在这里插入图片描述

Number

在这里插入图片描述

综合案例

在这里插入图片描述

<!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 .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 <span class="tag">【赠品】10优惠券</span></p>
      <p class="spec">白色/10寸</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' }
      },
      {
        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: 1,
        spec: { size: '小号', color: '紫色' },
        gift: '50g茶叶,清洗球'
      }
    ]

    document.querySelector('.list').innerHTML = goodsList.map(item => {
      const { id, name, price, picture, count, spec, gift } = item
      const text = Object.values(spec).join('/')
      const str = gift ? gift.split(',').map(item => `<span class="tag">【赠品】${item}</span>`).join('') : ''
      const subtotal = ((price * 100 * count) / 100).toFixed(2)
      return `
      <div class="item">
      <img src="${picture}" alt="">
      <p class="name">${name} ${str}</p>
      <p class="spec">${text}</p>
      <p class="price">${price.toFixed(2)}</p>
      <p class="count">x${count}</p>
      <p class="sub-total">${subtotal}</p>
    </div>
      `
    }).join('')
    const total = goodsList.reduce((prev, item) => prev + (item.price * 100 * item.count) / 100, 0)
    document.querySelector('.amount').innerHTML = total.toFixed(2)

  </script>
</body>

</html>