global namespace object

// global object

var MYAPP = {};

// constructors

MYAPP.Parent = function() {
}; MYAPP.Child = function() {
}; // a variable MYAPP.some_var = 1; // an object container MYAPP.modules = {}; // nested objects MYAPP.modules.module1 = {}; MYAPP.modules.module1.data = {
a : 1,
b : 2
}; MYAPP.modules.module2 = {};

Drawbacks

• A bit more to type; prefixing every variable and function does add up in the total amount of code that needs to be downloaded

• Only one global instance means that any part of the code can modify the global instance and the rest of the functionality gets the updated state

• Long nested names mean longer (slower) property resolution lookups

General Purpose Namespace Function

// unsafe

var MYAPP = {};

// better

if ( typeof MYAPP === "undefined") {

    var MYAPP = {};

}

// or shorter

var MYAPP = MYAPP || {};

// using a namespace function

MYAPP.namespace('MYAPP.modules.module2');

// equivalent to:

// var MYAPP = {

//      modules: {

//              module2: {}

//      }

// };

MYAPP.namespace = function(ns_string) {

    var parts = ns_string.split('.'), parent = MYAPP, i;

    // strip redundant leading global

    if (parts[0] === "MYAPP") {

        parts = parts.slice(1);

    }

    for ( i = 0; i < parts.length; i += 1) {

        // create a property if it doesn't exist

        if ( typeof parent[parts[i]] === "undefined") {

            parent[parts[i]] = {};

        }

        parent = parent[parts[i]];

    }

    return parent;

};

// assign returned value to a local var

var module2 = MYAPP.namespace('MYAPP.modules.module2');

module2 === MYAPP.modules.module2;
// true // skip initial `MYAPP` MYAPP.namespace('modules.module51'); // long namespace MYAPP.namespace('once.upon.a.time.there.was.this.long.nested.property');

 References: 

JavaScript Patterns - by Stoyan Stefanov (O`Reilly)

JavaScript Patterns 5.1 Namespace Pattern的更多相关文章

  1. JavaScript Patterns 5.5 Sandbox Pattern

    Drawbacks of the namespacing pattern • Reliance on a single global variable to be the application’s ...

  2. JavaScript Patterns 5.4 Module Pattern

    MYAPP.namespace('MYAPP.utilities.array'); MYAPP.utilities.array = (function () { // dependencies var ...

  3. JavaScript Patterns 5.8 Chaining Pattern

    Chaining Pattern - Call methods on an object one after the other without assigning the return values ...

  4. JavaScript Patterns 4.2 Callback Pattern

    function writeCode(callback) { // do something... callback(); // ... } function introduceBugs() { // ...

  5. JavaScript Patterns 2.6 switch Pattern

    Principle • Aligning each case with switch(an exception to the curly braces indentation rule). • Ind ...

  6. JavaScript Patterns 4.8 Function Properties - A Memoization Pattern

    Gets a length property containing the number of arguments the function expects: function func(a, b, ...

  7. JavaScript Patterns 7.1 Singleton

    7.1 Singleton The idea of the singleton pattern is to have only one instance of a specific class. Th ...

  8. JavaScript Patterns 6.7 Borrowing Methods

    Scenario You want to use just the methods you like, without inheriting all the other methods that yo ...

  9. JavaScript Patterns 6.5 Inheritance by Copying Properties

    Shallow copy pattern function extend(parent, child) { var i; child = child || {}; for (i in parent) ...

随机推荐

  1. ASP.NET MVC 请求流程:Route

    1.RouteTable RouteTable翻译过来的意思就是路由表,一个Web应用程序具有一个全局的路由表,该路由表通过System.Web.Routiing.RouteTable的静态只读属性R ...

  2. iOS阶段学习第18天笔记(Plist-Archiver-归档与解归档操作)

    iOS学习(OC语言)知识点整理 一.归档与解归档的操作 1)归档是一个过程,将一个或多个对象存储起来,以便以后可以还原,包括将对象存入文件,以后再读取 将数据对象归档成plist文件 2)plist ...

  3. 基于.Net Framework 4.0 Web API开发(3):ASP.NET Web APIs 异常的统一处理Attribute 和统一写Log 的Attribute的实现

    概述:  ASP.NET Web API 的好用使用过的都知道,没有复杂的配置文件,一个简单的ApiController加上需要的Action就能工作.但是项目,总有异常发生,本节就来谈谈API的异常 ...

  4. 【Java每日一题】20161121

    package Nov2016.use01; class Test { public String getString(){ return "123"; } } package N ...

  5. hibernate3

    hibernate3 (整合到spring中的core核心配置中的hibernate3) <!-- 基于hibernate的Session工厂 --> <bean id=" ...

  6. 操作系统与c语言

      以下是根据看书后的理解做的总结:   最早,unix是使用汇编编写,但是非常简单.后来觉得汇编,换种机器又得重新用另外一种机器汇编重写,太麻烦.于是想设计一种通用的语言,到各种机器上都能运行 当时 ...

  7. Java经典实例:比较浮点数

    /** * Created by Frank * 比较浮点数 */ public class FloatCmp { // 公差 private final static Double EPSILON ...

  8. Git修改提交的用户名和Email

    git config --global user.name "Your Name" git config --global user.email you@example.com

  9. jQuery超酷下拉插件6种效果演示

    原始的下拉框很丑啦, 给大家一款jQuery超酷下拉插件6种效果 效果预览 下载地址 实例代码 <div class="container"> <section ...

  10. Strip JS – 低侵入,响应式的 Lightbox 效果

    Strip  是一个灯箱效果插件,显示的时候只会覆盖部分的页面,这使得侵扰程度较低,并留出了空间与页面上的大屏幕,同时给予小型移动设备上的经典灯箱体验.Strp JS 基于 jQuery 库实现,支持 ...