ES6基础与解构赋值（高颜值弹框小案例！）

发布时间：2020-12-16 04:21:54 所属栏目：百科来源：网络整理

导读：let只作用在当前块级作用域内使用let或者const声明的变量，不能再被重新声明 let不存在`变量提升` console.log(dad); var dad = '我是爸爸!'; // 预定义undefined console.log(dad); let dad = '我是爸爸!'; 报错生成十个按钮每个按点击的时候弹出1 - 10

let只作用在当前块级作用域内
使用let或者const声明的变量，不能再被重新声明
let不存在`变量提升`

    console.log(dad);
    var dad = '我是爸爸!';//预定义undefined

    console.log(dad);
    let dad = '我是爸爸!';报错

生成十个按钮每个按点击的时候弹出1 - 10
var 方法：

    var i = 0;
    for (i = 1; i <= 10; i ++) {
      (function(i) {
        var btn = document.createElement('button');
        btn.innerText = i;
        btn.onclick = () {
          alert(i)
        };
        document.body.appendChild(btn);
      })(i);
    }

let方法：

    for (let i = 1; i <= 10; i ++) {
      );
      btn.innerText = i;
      btn.onclick = () {
        alert(i)
      };
      document.body.appendChild(btn);
    }

ES6之前的作用域：全局作用域、函数作用域、eval作用域、ES6块级作用域

常量声明后不能被修改

  const NAME = '小明';
  NAME = '小红';报错

q: 怎么防止常量为引用类型的时候能被修改的情况
Object.freeze()

    const xiaoming = {
      age: 14,name: '小明'
    };
    Object.freeze(xiaoming);
    console.log(xiaoming);
    xiaoming.age = 22;
    xiaoming.dd = 11;
    console.log(xiaoming);

    const ARR = [];
    Object.freeze(ARR);
    ARR.push(1);
    console.log(ARR);

Object的hasOwnProperty()方法返回一个布尔值，判断对象是否包含特定的自身（非继承）属性

    var obj1 = {
        a: 1
    }

    var obj2 = Object.create(obj1);

    obj2.c = 3;
    obj2.d = 4;

    for (let i in obj2) {
        if (obj2.hasOwnProperty(i)) {
            document.body.innerHTML += (i + ': ' + obj2[i] + '<br>');
        }
    }

数组的解构赋值

    const arr = [1,2,3,4];
    let [a,b,c,d] = arr;
    console.log(a);

更复杂的匹配规则

    const arr = ['a','b',['c','d',['e','f','g']]];
    const [,b] = arr;
    const [,g] = ['e',1)">]
    const [,[,g]] = ['c',1)">]];
    const [,g]]] = arr;

扩展运算符? ...

    const arr1 = [1,3];
    const arr2 = ['a','b'];
    const arr3 = ['zz',1];
    const arr4 = [...arr1,...arr2,...arr3];
    const arr = [1,4,5,6];
    const [a,...c] = arr;

默认值

    const arr = [1,null
    [a,b] = [b,a];

接收多个函数返回值

     getUserInfo(id) {
       .. ajax
      return [
        true'女'
      ];
    };
    const [status,data,msg] = getUserInfo(123);

对象的解构赋值

    const obj = {
        saber: '阿尔托利亚'
    };
    const { saber,archer1 } = obj;

稍微复杂的解构条件

    const player = {
        nickname: '感情的戏∫我没演技?''龙吟'6000
        },{
            skillName: '龙卷雨击'3000'900'
        }]
    };

    const { nickname } = player;
    const { master } = player;
    const { skill: [ skill1,{ skillName },{ skillName: sklName } ] } = player;
    const { skill } = player;
    const [ skill1 ] = skill;

结合扩展运算符

    const obj == obj;

对已经申明了的变量进行对象的解构赋值

    let age;
    const obj = {
        name: '小明'
    };
    ({ age } = obj);

默认值

    let girlfriend = {
        name: '小红'
    const str = 'I am the bone of my sword';  我是剑骨头
    const [ a,...oth ] = str;
    const [ ...spStr1 ] = str;

提取属性

    const { length,split } = str;

数值与布尔值的解构赋值

    const { valueOf: vo } = 1;
    const { toString: ts } = false;

函数参数的解构赋值

     swap([x,y]) {
         [y,x];
    };

    let arr = [1,2];
    arr = swap(arr);

     Computer({
        cpu,memory,software = ['ie6'],OS = 'windows 3.5'
    }) {

        console.log(cpu);
        console.log(memory);
        console.log(software);
        console.log(OS);

    };

    new Computer({
        memory: '128G''windows 10'
    });

最后来一个高颜值弹框小案例~

按照国际惯例先放图

index.html

    <!DOCTYPE html>
    <html lang="en"head>
      meta charset="UTF-8"name="viewport" content="width=device-width,initial-scale=1.0"http-equiv="X-UA-Compatible"="ie=edge"title>Document</link rel="stylesheet" href="./msg.css"bodybutton>弹个框div id="t"></divscript src="./msg.js"script>
        document.querySelector('button).addEventListener(clickfunction() {
          new $Msg({
            content: 真的要删除吗...确认删除wrong好的算了吧(e) {
              console.log(this);
              console.log(e);
               $Msg({
                content: 删除成功<span style="color: red">～</span>successfalsetrue
              })
            },cancel: (e) {
              document.querySelector(#t).innerHTML += 取消了，;
            }
          });
        });
      html>

msg.css

    /* 弹出框最外层 */
    .msg__wrap {
      position: fixed;
      top: 50%;
      left:
      z-index: 10;
      transition: all .3s;
      transform: translate(-50%,-50%) scale(0,0);
      max-width:
      
      background: #fff;
      box-shadow: 0 0 10px #eee;
      font-size: 10px;
    }

     弹出框头部 
    .msg__wrap .msg-header {
      padding: 10px 10px 0 10px; 1.8em;
    }

    .msg__wrap .msg-header .msg-header-close-button {
      float: right;
      cursor: pointer;
    }

     弹出框中部 
    .msg__wrap .msg-body { 10px 10px 10px 10px;
      display: flex;
    }

     图标 
    .msg__wrap .msg-body .msg-body-icon{
      width: 80px;
    }

    .msg__wrap .msg-body .msg-body-icon div{ 45px;
      height:
      margin: 0 auto;
      line-height:
      color:
      border-radius: 50% 50%; 2em;
    }

    .msg__wrap .msg-body .msg-body-icon .msg-body-icon-success{
      background: #32a323;
      text-align: center;
    }

    .msg__wrap .msg-body .msg-body-icon .msg-body-icon-success::after{
      content: "成";
    }

    .msg__wrap .msg-body .msg-body-icon .msg-body-icon-wrong{ #ff8080;

    .msg__wrap .msg-body .msg-body-icon .msg-body-icon-wrong::after{ "误";
    }

    .msg__wrap .msg-body .msg-body-icon .msg-body-icon-info{ #80b7ff;

    .msg__wrap .msg-body .msg-body-icon .msg-body-icon-info::after{ "注";
    }

     内容 
    .msg__wrap .msg-body .msg-body-content{
      min-width: 200px; 1.5em;
      word-break: break-all; flex;
      align-items: center;
      padding-left: 10px;
      box-sizing: border-box;
    }

     弹出框底部 
    .msg__wrap .msg-footer { 0 10px 10px 10px;
      flex-direction: row-reverse;
    }

    .msg__wrap .msg-footer .msg-footer-btn { 50px; 30px;
      border: 0 none;
      outline: none; 1em; 2px;
      margin-left: 5px; pointer;
    }

    .msg__wrap .msg-footer .msg-footer-cancel-button{
      background-color: #ff3b3b;
    }

    .msg__wrap .msg-footer .msg-footer-cancel-button:active{ #ff6f6f;
    }

    .msg__wrap .msg-footer .msg-footer-confirm-button{ #4896f0;
    }

    .msg__wrap .msg-footer .msg-footer-confirm-button:active{ #1d5fac;
    }

     遮罩层 
    .msg__overlay { 0;
      right:
      bottom: 5; rgba(0,.4);
      opacity: 0;
    }

msg.js

    ( (window,document) {

      *
       * 暴露出去的构造函数
       * @param {*} options 
       */
      let Msg =  (options) {
        this._init(options);
      }

      *
       * 初始化传入的配置后创建元素 并显示
       * @param {*} param0 
       
      Msg.prototype._init =  ({ 
        content = ''= false= = = '提示' {},contentFontSize = '1.5em']
      }) {
        this.content = content;
        this.type = type;
        this.useHTML = useHTML;
        this.showIcon = showIcon;
        this.confirm = confirm;
        this.cancel = cancel;
        this.footer = footer;
        this.contentStyle = contentStyle;
        this.contentFontSize = contentFontSize;
        this.title = title;
        this.btnName = btnName;
        this.header = header;

        ._createElement();
         给dom上的按钮们和遮罩层绑定事件
        this._bind({ el: this._el,overlay: ._overlay });
        this._show({ el: ._overlay });
      }

      *
       * 创建弹出框
       
      Msg.prototype._createElement =  () {

        let wrap = document.createElement('div');
        wrap.className = 'msg__wrap';

        const [ confirmBtnName,cancelBtnName ] = .btnName;

         判断是否显示图标
        const iconHTML = .showIcon 
          ? '<div class="msg-body-icon">
              <div class="msg-body-icon-' + this.type + '"></div>
            </div>' 
          : '';

         判断是否显示弹出框底部按钮
        const footerHTML = .footer 
          ? '<div class="msg-footer">
              <button class="msg-footer-btn msg-footer-cancel-button">' + cancelBtnName + '</button>
              <button class="msg-footer-btn msg-footer-confirm-button">' + confirmBtnName + '</button>
            </div>' : '';

        const headerHTML = .header
          ? '<div class="msg-header">
              <span>' + this.title + '</span>
              <span class="msg-header-close-button">×</span>
            </div>'
          : '' 拼成完整html
        const innerHTML = headerHTML +
                          '<div class="msg-body">' 
                            + iconHTML + 
                            '<div class="msg-body-content"></div>
                          </div>'
                          + footerHTML;

         将容器内的html替换成弹出框内容
        wrap.innerHTML = innerHTML;

         生成合并自定义的内容样式
        const contentStyle = {
          fontSize: .contentFontSize,....contentStyle
        }

         获取内容dom
        let content = wrap.querySelector('.msg-body .msg-body-content');

         给内容容器加上自定义样式
        for (let key  contentStyle) {
          content.style[key] = contentStyle[key];
        }

         给弹出框内容赋值
        if (.useHTML) {
          content.innerHTML = .content;
        } else {
          content.innerText = .content;
        }

         创建遮罩层
        let overlay = document.createElement('div');
        overlay.className = 'msg__overlay' 把dom挂到当前实例上
        this._overlay = overlay;
        this._el = wrap;
      }

      *
       * 显示弹出框
       * @param {*} param0 
       
      Msg.prototype._show =  ({ el,overlay }) {

         把遮罩和弹出框插到页面中
        document.body.appendChild(el);
        document.body.appendChild(overlay);

         显示
        setTimeout( () {
          el.style.transform = 'translate(-50%,-50%) scale(1,1)';
          overlay.style.opacity = '1';
          console.log(1);
        });
        console.log(2);
      }

      *
       * 绑定事件
       * @param {*} param0 
       
      Msg.prototype._bind =  保留this
        const _this =  隐藏弹出框
        const hideMsg =  () {
          _this._el.style.transform = 'translate(-50%,0)';
          _this._overlay.style.opacity = '0';

          setTimeout( () {
            document.body.removeChild(_this._el);
            document.body.removeChild(_this._overlay);
          },300);
        }

         取消事件
        const close =  (e) {
          _this.cancel && _this.cancel.call(_this,e);
          hideMsg();
        }

         确定事件
        const confirm =  (e) {
          _this.confirm && _this.confirm.call(_this,e);
          hideMsg();
        }

        overlay.addEventListener('click'.header) {
          el.querySelector('.msg-header .msg-header-close-button').addEventListener('click'.footer) {
          el.querySelector('.msg-footer .msg-footer-cancel-button').addEventListener('click' 注册到全局对象
      window.$Msg = Msg;

    })(window,document);

（编辑：李大同）

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