如何在JavaScript中创建命名空间,使我的对象和函数不被其他同名对象和函数覆盖?我使用了以下方法:

if (Foo == null || typeof(Foo) != "object") { var Foo = new Object();}

有没有更优雅或更简洁的方式来做到这一点?


当前回答

示例:

var namespace = {};
namespace.module1 = (function(){

    var self = {};
    self.initialized = false;

    self.init = function(){
        setTimeout(self.onTimeout, 1000)
    };

    self.onTimeout = function(){
        alert('onTimeout')
        self.initialized = true;
    };

    self.init(); /* If it needs to auto-initialize, */
    /* You can also call 'namespace.module1.init();' from outside the module. */
    return self;
})()

你可以声明一个局部变量,就像self和assign local。onTimeout如果你想要它是私有的。

其他回答

我喜欢Jaco Pretorius的解决方案,但我想通过将“this”关键字指向模块/名称空间对象来使其更有用。 我的煎锅版本:

(function ($, undefined) {

    console.log(this);

}).call(window.myNamespace = window.myNamespace || {}, jQuery);

在将我的几个库移植到不同的项目中,并且不得不不断更改顶级(静态命名的)名称空间之后,我转而使用这个小的(开源的)帮助函数来定义名称空间。

global_namespace.Define('startpad.base', function(ns) {
    var Other = ns.Import('startpad.other');
    ....
});

关于好处的描述在我的博客文章中。您可以在这里获取源代码。

我非常喜欢的一个好处是模块之间相对于加载顺序的隔离。你可以在加载外部模块之前引用它。当代码可用时,将填充您获得的对象引用。

下面是Stoyan Stefanov在他的JavaScript Patterns一书中是如何做到这一点的,我发现这本书非常好(它还展示了他如何做注释,允许自动生成API文档,以及如何向自定义对象的原型添加一个方法):

/**
* My JavaScript application
*
* @module myapp
*/

/** @namespace Namespace for MYAPP classes and functions. */
var MYAPP = MYAPP || {};

/**
* A maths utility
* @namespace MYAPP
* @class math_stuff
*/
MYAPP.math_stuff = {

    /**
    * Sums two numbers
    *
    * @method sum
    * @param {Number} a First number
    * @param {Number} b Second number
    * @return {Number} Sum of the inputs
    */
    sum: function (a, b) {
        return a + b;
    },

    /**
    * Multiplies two numbers
    *
    * @method multi
    * @param {Number} a First number
    * @param {Number} b Second number
    * @return {Number} The inputs multiplied
    */
    multi: function (a, b) {
        return a * b;
    }
};

/**
* Constructs Person objects
* @class Person
* @constructor
* @namespace MYAPP
* @param {String} First name
* @param {String} Last name
*/
MYAPP.Person = function (first, last) {

    /**
    * First name of the Person
    * @property first_name
    * @type String
    */
    this.first_name = first;

    /**
    * Last name of the Person
    * @property last_name
    * @type String
    */
    this.last_name = last;
};

/**
* Return Person's full name
*
* @method getName
* @return {String} First name + last name
*/
MYAPP.Person.prototype.getName = function () {
    return this.first_name + ' ' + this.last_name;
};

如果你需要私有作用域:

var yourNamespace = (function() {

  //Private property
  var publicScope = {};

  //Private property
  var privateProperty = "aaa"; 

  //Public property
  publicScope.publicProperty = "bbb";

  //Public method
  publicScope.publicMethod = function() {
    this.privateMethod();
  };

  //Private method
  function privateMethod() {
    console.log(this.privateProperty);
  }

  //Return only the public parts
  return publicScope;
}());

yourNamespace.publicMethod();

否则,如果你永远不会使用私有作用域:

var yourNamespace = {};

yourNamespace.publicMethod = function() {
    // Do something...
};

yourNamespace.publicMethod2 = function() {
    // Do something...
};

yourNamespace.publicMethod();

我使用在企业jQuery网站上找到的方法:

下面是他们的例子,展示了如何声明私有和公共属性和函数。一切都是作为一个自动执行的匿名函数完成的。

(function( skillet, $, undefined ) {
    //Private Property
    var isHot = true;

    //Public Property
    skillet.ingredient = "Bacon Strips";

    //Public Method
    skillet.fry = function() {
        var oliveOil;

        addItem( "\t\n Butter \n\t" );
        addItem( oliveOil );
        console.log( "Frying " + skillet.ingredient );
    };

    //Private Method
    function addItem( item ) {
        if ( item !== undefined ) {
            console.log( "Adding " + $.trim(item) );
        }
    }
}( window.skillet = window.skillet || {}, jQuery ));

如果你想访问某个公共成员你只需输入skillet。fry()或skillet。配料。

真正酷的是,现在可以使用完全相同的语法扩展名称空间。

//Adding new Functionality to the skillet
(function( skillet, $, undefined ) {
    //Private Property
    var amountOfGrease = "1 Cup";

    //Public Method
    skillet.toString = function() {
        console.log( skillet.quantity + " " +
                     skillet.ingredient + " & " +
                     amountOfGrease + " of Grease" );
        console.log( isHot ? "Hot" : "Cold" );
    };
}( window.skillet = window.skillet || {}, jQuery ));

第三个未定义的参数

The third, undefined argument is the source of the variable of value undefined. I'm not sure if it's still relevant today, but while working with older browsers / JavaScript standards (ecmascript 5, javascript < 1.8.5 ~ firefox 4), the global-scope variable undefined is writable, so anyone could rewrite its value. The third argument (when not passed a value) creates a variable named undefined which is scoped to the namespace/function. Because no value was passed when you created the name space, it defaults to the value undefined.