JS中类的生成及继承，常用的数组和字符串的API

1.JS中的类的生成及继承

S中类用class关键字表示，
类中的几个关键1.构造函数constructor;2.静态数据 ：static；3.私有数据：# 4.方法；5.访问器函数 get set；6.继承：extends 继承中super的使用

1.1类的生成

console.log("-------------------------------");
console.log("形成一个User的类\n");
let User = class{
    constructor(name ,address,favorite){
        this.name = name;
        this.address = address;
        this.favorite = favorite;
    }
   static gender = "male";
   getUserInfo(){
    return `你的姓名是:${this.name}\n你的地址是:${this.address}\n你的爱好是:${this.favorite}\n`;
   }
}
let me = new User("jiao","peking","reading");
console.log(me.getUserInfo());

1.2 类的继承 extends

class Child extends User {
    constructor(name,address,favorite,tel){   //把父类的全部属性写上
      super(name,address,favorite);
      this.tel = tel;
    }
    // 继承父类的方法
    getUserInfo(){
        return `${super.getUserInfo()}您的电话是:${this.tel}`;
    }
}
let child_1 = new Child("wang","hefei","sport","1388");
console.log(child_1.getUserInfo());

1.3 类的访问器属性

class Descendent extends Child{
     constructor(name,address,favorite,tel,age){
        super(Child);
        this.age= age;
     }
    #gender = "male";
    get gender() { 
        return this.#gender;
    }
    set gender(a) {
        this.#gender = a;
    }
    }
    let des_1 = new Descendent("li","sd","reading","323",32);
    console.log(des_1.gender);
    console.log("变换gender的值");
    des_1.gender = "female";
    console.log(des_1.gender);

2.字符串中常用的API

    let str = "hello the world ";
    let str_2 ="again";
    // 2.1indexOf查找字符串中某个字符第一次出现的位置；
     console.log(str.indexOf("l"));
    // 2.2 concat合并两个字符串
     console.log(str.concat(str_2));
    // 2.3 slice() 获得指定位置之后的片段字符
     console.log(str.slice(3))
    // 2.4 replace( ),取代字符串中的某些字符
      console.log(str.replace("the","my"));
    // 2.5 匹配字符中的某些字符
    console.log(str.match(/the/));
    console.log('--------------------------');

3.数组常用的API

    console.log("数组常用的API");
    let arr_1 = [1,2,30,23];
    let arr_2 = [4,5];
    //3.1 求和 reduce
    console.log(arr_1.reduce((acc,cur)=> acc + cur));
    // 3.2. 遍历 map() 并返回数组
    let arr_map = arr_1.map(cur => cur +=2);
    console.log(arr_map);
    // 3.3 concat()合并数组
    console.log(arr_1.concat(arr_2));
    // 3.4 取得数组中的片段
    console.log(arr_1.slice(2));
    //   3.5 数组扩项与减项 pop push
    console.log(arr_1.pop(3));
    console.log(arr_1);
    console.log(arr_1.push(45));
    console.log(arr_1);