24.ES11

私有属性

        class Person{
            //公有属性
            name;
            //私有属性
            #age;
            #weight;
            //构造方法
            constructor(name, age, weight){
                this.name = name;
                this.#age = age;
                this.#weight = weight;
            }

            intro(){
                console.log(this.name);
                console.log(this.#age);
                console.log(this.#weight);
            }
        }

        //实例化
        const girl = new Person('晓红', 18, '45kg');

        // console.log(girl.name);
        // console.log(girl.#age);//不能获取私有属性
        // console.log(girl.#weight);//不能获取私有属性

        girl.intro();//内部可以获取

Promise.allSettled

        //声明两个promise对象
        const p1 = new Promise((resolve, reject)=>{
            setTimeout(()=>{
                resolve('商品数据 - 1');
            },1000)
        });

        const p2 = new Promise((resolve, reject)=>{
            setTimeout(()=>{
                resolve('商品数据 - 2');
                // reject('出错啦!');
            },1000)
        });

        //调用 allsettled 方法
        const result = Promise.allSettled([p1, p2]);
        
        const res = Promise.all([p1, p2]);

        console.log(res);

String.prototype.matchAll

        let str = `<ul>
            <li>
                <a>肖生克的救赎</a>
                <p>上映日期: 1994-09-10</p>
            </li>
            <li>
                <a>阿甘正传</a>
                <p>上映日期: 1994-07-06</p>
            </li>
        </ul>`;

        //声明正则
        const reg = /<li>.*?<a>(.*?)<\/a>.*?<p>(.*?)<\/p>/sg

        //调用方法
        const result = str.matchAll(reg);

        // for(let v of result){
        //     console.log(v);
        // }

        const arr = [...result];

        console.log(arr);

可选链操作符

        // ?.
        function main(config){
            // const dbHost = config && config.db && config.db.host;
            const dbHost = config?.db?.host;

            console.log(dbHost);
        }

        main({
            db: {
                host:'192.168.1.100',
                username: 'root'
            },
            cache: {
                host: '192.168.1.200',
                username:'admin'
            }
        })

动态 import

<body>
    <button id="btn">点击</button>
    <script src="./js/app.js" type="module"></script>
</body>

//hello.js
export function hello(){
    alert('Hello');
}

//app.js
// import * as m1 from "./hello.js";
//获取元素
const btn = document.getElementById('btn');

btn.onclick = function(){
    import('./hello.js').then(module => {
        module.hello();
    });
}

BigInt

        //大整形
        let n = 521n;
        console.log(n, typeof(n));

        //函数
        let n = 123;
        console.log(BigInt(n));
        console.log(BigInt(1.2));

        //大数值运算
        let max = Number.MAX_SAFE_INTEGER;
        console.log(max);
        console.log(max + 1);
        console.log(max + 2);

        console.log(BigInt(max))
        console.log(BigInt(max) + BigInt(1))
        console.log(BigInt(max) + BigInt(2))

globalThis

console.log(globalThis);

posted @ 2021-02-05 18:50 AaronHuang 阅读(53) 评论(0) 编辑收藏举报

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