JavaScript面向对象三个基本特征实例详解【封装、继承与多态】

class Employees {
  constructor(name,age){
    this.name = name;
    this.age = age;
  }
  getInfo(){
    let {name,age} = this;
    return {name,age};
  }
  static seyHi(){
    console.log("Hi");  
  }
}

let lisi = new Employees("Aaron",18);
lisi.seyHi();  // lisi.seyHi is not a function
lisi.getInfo(); // {name: "Aaron", age: 18}
Employees.seyHi(); // Hi

Promise.then() // Promise.then is not a function
let p1 = new Promise(() => {})
p1.then(); // Promise {<pending>}
Promise.all([1]);  // Promise {<resolved>: Array(1)}

class Employees {
  constructor(name){
    this.name = name;
  }
  getName(){
    console.log(this.name)
  }
  static seyHi(){
    console.log("Hi");  
  }
}
class Java extends Employees{
  constructor(name){
    super(name);
  }
  work(){
    console.log("做后台工作");
  }
}
let java = new Java("Aaron");
java.getName();
java.work();
// java.seyHi();  // java.seyHi is not a function

class Employees {
  constructor(name){
    this.name = name;
  }
  seyHello(){
    console.log("Hello")
  }
  getName(){
    console.log(this.name);
  }
}
class Java extends Employees{
  constructor(name){
    super(name);
  }
  seyHello(){
    console.log(`Hello,我的名字是${this.name},我是做Java工作的。`)
  }
}
const employees = new Employees("Aaron");
const java = new Java("Leo");
employees.seyHello();  // Hello
java.seyHello();  // Hello,我的名字是Leo,我是做Java工作的。
employees.getName();  // Aaron
java.getName(); // Leo

class Employees {
  constructor(arg){
    let obj = null;
    switch(typeof arg)
    {
      case "string":
         obj = new StringEmployees(arg);
         break;
      case "object":
         obj = new ObjEmployees(ObjEmployees);
         break;
      case "number":
        obj = new NumberEmployees(ObjEmployees);
        break;
    }
    return obj;
  }
}
class ObjEmployees {
  constructor(arg){
    console.log("ObjEmployees")
  }
}
class StringEmployees {
  constructor(arg){
    console.log("StringEmployees")
  }
}
class NumberEmployees {
  constructor(arg){
    console.log("NumberEmployees")
  }
}
new Employees({})  // ObjEmployees
new Employees("123456") // StringEmployees
new Employees(987654)  // NumberEmployees