JavaScript面向对象的程序设计(犯迷糊的小羊)

好的。首先，JavaScript是一门基于对象的编程语言。它提供了许多面向对象编程的特性，如对象、类、继承等。如果您曾经在其他编程语言中使用过面向对象编程，那么理解JavaScript的面向对象编程会相对轻松些。

一、对象

面向对象编程的基础是对象。JavaScript中的对象是一个键-值对的集合，其中值可以是属性或方法。对象可以通过字面量或构造函数创建。

对象字面量：

var myObject = {
  firstName: "John",
  lastName: "Doe",
  fullName: function() {
    return this.firstName + " " + this.lastName;
  }
};

构造函数：

function Person(firstName, lastName) {
  this.firstName = firstName;
  this.lastName = lastName;
  this.fullName = function() {
    return this.firstName + " " + this.lastName;
  }
}

var person = new Person("John", "Doe");

二、类

类是一种蓝图或模板，用于创建对象的结构。在JavaScript中，类是通过构造函数和原型来定义的。

构造函数：

function Person(firstName, lastName) {
  this.firstName = firstName;
  this.lastName = lastName;
}

Person.prototype.fullName = function() {
  return this.firstName + " " + this.lastName;
}

上面的代码中，我们使用构造函数创建了一个Person类，并使用原型在Person类中添加了fullName方法。这样我们可以使用new关键字来实例化Person类的对象。

var person = new Person("John", "Doe");
console.log(person.fullName()); // John Doe

三、继承

继承是面向对象编程的一个重要概念，它允许我们从一个基类/父类中继承属性和方法，并在子类中添加新的属性和方法。

在JavaScript中，我们可以使用原型链来实现继承。要实现继承，我们需要设置子类的原型为父类的实例。这样子类就可以访问到父类的属性和方法。

function Shape(color) {
  this.color = color;
}

Shape.prototype.draw = function() {
  return "Drawing a shape with the color " + this.color;
}

function Rectangle(color, width, height) {
  Shape.call(this, color);
  this.width = width;
  this.height = height;
}

Rectangle.prototype = Object.create(Shape.prototype);
Rectangle.prototype.constructor = Rectangle;
Rectangle.prototype.draw = function() {
  return "Drawing a rectangle with the color " + this.color + ", width " + this.width + " and height " + this.height;
}

var rectangle = new Rectangle("red", 100, 50);
console.log(rectangle.draw()); // Drawing a rectangle with the color red, width 100 and height 50

上面的代码中，我们使用Shape类创建了一个Rectangle类，并通过原型链继承Shape的属性和方法。同时，在Rectangle类中我们重载了Shape的draw方法。

示例一：汽车继承

function Car(make, model, year) {
  this.make = make;
  this.model = model;
  this.year = year;
}

Car.prototype.getMakeModelYear = function() {
  return this.make + ' ' + this.model + ' ' + this.year;
}

function ElectricCar(make, model, year, range) {
  Car.call(this, make, model, year);
  this.range = range;
}

ElectricCar.prototype = Object.create(Car.prototype);
ElectricCar.prototype.constructor = ElectricCar;
ElectricCar.prototype.getMakeModelYearRange = function() {
  return this.getMakeModelYear() + ', ' + this.range + ' miles range';
}

var electricCar = new ElectricCar('Tesla', 'Model S', '2020', '370');
console.log(electricCar.getMakeModelYearRange()); //Tesla Model S 2020, 370 miles range

在上面的示例中，ElectricCar类继承自Car类，同时ElectricCar重新定义了一个getMakeModelYearRange方法来获取车的年款和里程数据。

示例二：员工继承

function Employee(name, title, department) {
  this.name = name;
  this.title = title;
  this.department = department;
}

Employee.prototype.getNameAndTitle = function() {
  return this.name + ' ' + this.title;
}

function Manager(name, title, department, reports) {
  Employee.call(this, name, title, department);
  this.reports = reports;
}

Manager.prototype = Object.create(Employee.prototype);
Manager.prototype.constructor = Manager;
Manager.prototype.getReports = function() {
  return this.name + ' is a ' + this.title + ' in ' + this.department + ' and has ' + this.reports.length + ' reports.';
}

var employee1 = new Employee('John Doe', 'Designer', 'Product Design');
console.log(employee1.getNameAndTitle()); // John Doe Designer

var manager = new Manager('Jane Smith', 'Manager', 'Product Design', [employee1]);
console.log(manager.getReports()); // Jane Smith is a Manager in Product Design and has 1 reports.

在上面的示例中，Manager类继承自Employee类，同时Manager定义了一个getReports方法来获取该经理下的报告人数量。