Implementing namespaces in JavaScript_javascript tips

Note: I haven’t written for a long time. Today I copied an article I wrote on the company’s intranet to show off my face. I just switched to web development, so I started learning javascript!

Before the introduction of namespaces, a headache for developers was how to prevent function names/class names from conflicting with others. Within a company, project teams could make reservations through naming (such as adding prefixes, etc.) To solve this problem, but looking at the entire software development field, in today's era when collaborative development is quite popular, this problem still exists. When using multiple third-party frameworks or libraries, the only thing you can do is to pray that their naming does not conflict. If such a disaster really occurs, the only thing you can do is to abandon one of them (Note: Maybe I am ignorant) ,hehe). The introduction of namespaces has solved this problem to a considerable extent. Of course, if the namespace you use is unfortunately the same as that of other companies, and the other company is Microsoft, SUN, etc., then congratulations, haha@_@!

It is inevitable to be exposed to JavaScript when engaging in web development. The latest version of JavaScript still does not support namespaces, so the problem of naming conflicts is undoubtedly prominent. Imagine that you referenced two js files, but found that you had to give up due to naming problems. One of them, which leads to writing a lot of extra code, is undoubtedly very frustrating. Before the new version of JavaScript introduces the concept of namespaces, it is the basic obligation of our programmers to carry forward the spirit of self-reliance and creativity;-)

Prerequisite for implementation: Unlike languages ​​such as Delphi and C#, classes in JavaScript are not objects Definition, in fact there is no real class in JavaScript, the class here is actually implemented using function simulation, and the function in JavaScript is actually an object, so in JavaScript: a class is an object. This is very different from the traditional concept. In JavaScript, creating an instance of a class is actually making a copy of the class (= object, remember). Seeing this, you should be able to see some concept of design patterns. In JavaScript, the class mechanism uses the prototype pattern.

Implementation principle: Now that the essence of the class is clearly seen, the problem is simple. If all the JS classes and functions of the GEA project team are placed as attributes in an object named GEA, and then the GEA object is Our purpose can be achieved by placing it in an object named Grandsoft. For example, Grandsoft.GEA.Person is actually the class Person (still an object) in the attribute GEA of the Grandsoft object (also an object).

The implementation is very simple. The implementation of the entire namespace mechanism does not exceed 20 lines of code. The analysis is as follows:

// Declare a global object Namespace to register the namespace

Copy code The code is as follows:

Namespace = new Object();

// 전역 객체에는 등록 기능만 있고 매개변수는 "Grandsoft.GEA"
Namespace와 같은 네임스페이스의 전체 경로입니다. Register = function(fullNS)
{
// 네임스페이스를 Grandsoft, GEA 등 N 부분으로 나눕니다.
var nsArray = fullNS.split('.')
var sEval = "";
var sNS = "";
for (var i = 0; i < nsArray.length; i )
{
if (i != 0) sNS = ". ";
sNS = nsArray[ i];
// 네임스페이스 객체(존재하지 않는 경우)를 순서대로 구성하는 명령문을 생성합니다.
// 예를 들어 먼저 Grandsoft를 생성한 다음 Grandsoft.GEA를 생성합니다. , 그리고 순서대로 계속
sEval = "if (typeof( " sNS ") == 'undefine') " sNS " = new Object();"
}  
if (sEval != "") eval(sEval); JavaScript에서 시뮬레이션된 네임스페이스 메커니즘의 전체 구현은 다음과 같이 사용됩니다:


// 네임스페이스 Grandsoft.GEA, Grandsoft.GCM
Namespace.register("Grandsoft. GEA");
Namespace.register("Grandsoft.GCM");

// Grandsoft.GEA 네임스페이스에 Person 클래스 선언
Grandsoft.GEA.Person = 함수(이름, 나이)
{
this.name = name;
this.age = age
}

// Person 클래스에 show() 공개 메소드 추가
Grandsoft.GEA .Person.prototype .show = function()
{
Alert(this.name "은 " this.age " 세입니다!")
}

// 방법 시연 use class Person
var p = new Grandsoft.GEA.Person("yanglf", 25);
p.show()
하하, 간단합니다. 코드는 직접 보시면 됩니다. 사실 좀 게으른 편입니다. 하하@_@!!!