function Parent() {

  this.name = 'parent';

}

Parent.prototype.getName = function() {

  return this.name;

};

function Child() {}

Child.prototype = new Parent(); // 核心：子类原型是父类实例

const child = new Child();

console.log(child.getName()); // 'parent'

function Parent(name) {

  this.name = name;

  this.colors = ['red', 'blue'];

}

function Child(name) {

  Parent.call(this, name); // 核心：借用构造函数

}

const c1 = new Child('child1');

c1.colors.push('green');

const c2 = new Child('child2');

console.log(c1.colors); // ['red', 'blue', 'green']

console.log(c2.colors); // ['red', 'blue']

function Parent(name) {

  this.name = name;

  this.colors = ['red', 'blue'];

}

Parent.prototype.getName = function() {

  return this.name;

};

function Child(name, age) {

  Parent.call(this, name); // 第二次调用 Parent()

  this.age = age;

}

Child.prototype = new Parent(); // 第一次调用 Parent()

Child.prototype.constructor = Child;

Child.prototype.getAge = function() {

  return this.age;

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};

function inheritPrototype(Child, Parent) {

  const prototype = Object.create(Parent.prototype);

  prototype.constructor = Child;

  Child.prototype = prototype;

}

function Parent(name) {

  this.name = name;

}

Parent.prototype.getName = function() {

  return this.name;

};

function Child(name, age) {

  Parent.call(this, name);

  this.age = age;

}

inheritPrototype(Child, Parent); // 核心：不直接 new Parent()

class Parent {

  constructor(name) {

    this.name = name;

  }

  getName() {

    return this.name;

  }

}

class Child extends Parent {

  constructor(name, age) {

    super(name); // 调用父类 constructor

    this.age = age;

  }

  getAge() {

    return this.age;

  }

}