JS继承

1.基于原型的继承

子对象继承父对象属性或方法，需要将子对象的prototype等于父对象构造函数的实例

function Parent(name, age) {
 this.name = name;
 this.age = age;
 this.sayHi = function () {
     console.log("Hi");
 }
}
function Child(name, age) {
 this.name = name;
 this.age = age;
}
Child.prototype = new Parent()
const child = new Child()
child.sayHi()   //Hi

2.基于class的继承

类的继承用到extends，内部通过super()继承需要的属性

class Parent {
 constructor(name) {
     this.name = name
 }
 sayHi() {
     console.log("Hi");
 }
}
class Child extends Parent {
 constructor(name) {
     super(name)
 }
}
const child = new Child("frank")
console.log(child.name);    //frank
child.sayHi()       //Hi