JavaScript must know: Surface Object programming

The core concept of surface Object Programming Technology: encapsulation, inheritance, polymorphism; In some major high-level programming languages, such as: c#,vb.net,java,php, etc. are easy to implement, and if you want to implement polygon object programming in JavaScript, It's not so straightforward and easy, because JavaScript is not an object-oriented language, so we can only simulate object-oriented programming through some JavaScript features, such as closures, prototype chains, and so on, which I think are the basis for mastering and using JavaScript flexibly. , there are a lot of javascript gurus in the garden that are introduced and analyzed in this area, and I am only re-understanding JavaScript Object-oriented points as a project leader (independently designed and developed web front-end and back-end).

Since it is object-oriented, we first need to know how to create an object, and here are a few common ways to create an object:

A. Create an object instance directly:

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//直接实例化一个对象var Person1 = { Name: "梦在旅途", Age: 29, Sex: "男", Height: 178 }; alert(Person1.Name);var Person2 = new Object();Person2.Name = "梦在旅途";Person2.Age = 29;Person2.Sex = "男";Person2.Height = 178; alert(Person2.Name);//这个是上面的简写var Person3 = new Object({ Name: "梦在旅途", Age: 29, Sex: "男", Height: 178 });alert(Person3.Name);

Pros: Create an object directly without having to define the type in advance;

Disadvantage: unable to achieve reuse;

B. Defining a post-instantiation object first:

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//先定义类，再实例化成对象function Person4(n,a,s,h) {    this.Name = n;    this.Age = a;    this.Sex = s;    this.Height = h;}var p4 = new Person4("梦在旅途", 29, "男", 178);alert(p4.Age);

Pros: Similar to object-oriented programming language constructors, easy to understand, and after the definition can be instantiated through the New keyword multiple objects, to achieve reuse.

Disadvantage: Need to define before you can instantiate;

In summary, it is recommended to use the B method to create objects.

Implement encapsulation, which exposes only public and public properties, and hides implementation details (private methods, properties)

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function Person5(n, a, s, h) {    //公共属性    this.Name = n;    this.Age = a;    this.Sex = s;    this.Height = h;        //公共方法    this.AfterYear = function (count) {        updateAge(count);        alert(_currentYear +"后，我已经：" + this.Age +"岁了！");    };    this.Say = function () {        alert("我的个人信息－－> Name: "+ this.Name+", Age: "+ this.Age +", Sex: "+ this.Sex +", Height:" + this.Height);    }    //私有属性与方法    var _self = this;    var _currentYear = 2015;    function updateAge(count) {        _currentYear += count;        _self.Age += count;    };}var p5 = new Person5("梦在旅途", 29, "男", 178);p5.AfterYear(10);p5.AfterYear(25);

Using a prototype chain to implement inheritance, that is, one object contains all the public properties and methods of another object, there are many ways to implement inheritance, and I think the following form is used to simulate inheritance more consistent with object-oriented thinking:

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function SoftEngineer(n, a, s, h, lang) {    Person5.call(this, n, a, s, h);//将Person5的所有属性与方法包含到SoftEngineer中，从而实现继承    this.Lang = lang;    this.SayCode = function () {        alert("我是一名软件工程师，我会" + this.Lang + "编程语言！");    }    this.Working = function () { };//空方法，类似面向对象中的虚方法}SoftEngineer.prototype = new Person5(); //将SoftEngineer的原型指定Person5的实例var softengr = new SoftEngineer("梦在旅途", 29, "男", 178, "javascript");softengr.Say();softengr.SayCode();

The use of the prototype chain to achieve polymorphism, that is, based on the same method signature in different subclasses behave in different forms:

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function WebSoftEngineer(n, a, s, h, lang) {    SoftEngineer.apply(this, [n, a, s, h, lang]);    this.Working = function () {        alert("我是网页工程师，从事网页开发设计工作！");    };};WebSoftEngineer.prototype = new SoftEngineer();function AppSoftEngineer(n, a, s, h, lang) {    SoftEngineer.apply(this, [n, a, s, h, lang]);    this.Working = function () {        alert("我是应用工程师，从事客户端应用程序开发设计工作！");    };};AppSoftEngineer.prototype = new SoftEngineer();var webengr = new WebSoftEngineer("梦在旅途", 29, "男", 178, "javascript");webengr.Say();webengr.Working();var appengr = new AppSoftEngineer("梦在旅途", 29, "男", 178, "c#");appengr.Say();appengr.Working();

JavaScript must know: Surface Object programming