妙用class

收集自后盾人网站

1.利用class扩展内置类

class NewArr extends Array {
  constructor(...args) {
    super(...args);
  }
  first() {
    return this[0];
  }
  add(value) {
    this.push(value);
  }
  remove(value) {
    let pos = this.findIndex(curValue => {
      return curValue == value;
    });
    this.splice(pos, 1);
  }
}
let hd = new NewArr(5, 3, 2, 1);
console.log(hd.length); //4
console.log(hd.first()); //5

hd.add("houdunren");
console.log(hd.join(",")); //5,3,2,1,houdunren

hd.remove("3");
console.log(hd.join(",")); //5,2,1,houdunren

2.mixin

JS不能实现多继承，如果要使用多个类的方法时可以使用mixin混合模式来完成。

const Tool = {
  max(key) {
    return this.data.sort((a, b) => b[key] - a[key])[0];
  }
};

class Lesson {
  constructor(lessons) {
    this.lessons = lessons;
  }
  get data() {
    return this.lessons;
  }
}

Object.assign(Lesson.prototype, Tool);
const data = [
  { name: "js", price: 100 },
  { name: "mysql", price: 212 },
  { name: "vue.js", price: 98 }
];
let hd = new Lesson(data);
console.log(hd.max("price"));