The Module Pattern Module模式

jQuery, Dojo, ExtJS, YUI都用到了这种模式

"I'm currently in the process of writing a large-scale JavaScript application based on this pattern, and I have to say, it's a delight." ---- Brian Cray

优点

• Cleaner approach for developers 更加干净的接口
• Supports private data 支持私有数据
• Less clutter in the global namespace 在全局命名空间没那么杂乱
• Localization of functions and variables throught closures 通过闭包对方法和变量的本地化

缺点

• 私有方法无法访问，可能会不易测试
• 因为私有方法和函数不可访问，因此它们缺少可扩展性

例子一

( function( window, undefined ) {

  // normally variables & functions start with a lowercase letter but with modules, that is not the case.
  // The general tradition is to start them with a capital letter instead.
  function MyModule() {

    // `this` refers to the instance of `MyModule` when created
    this.myMethod = function myMethod() {
      alert( 'my method' );
    };

    // note that we still use a function declaration even when using a function expression.
    // for more information on why, check out: http://kangax.github.io/nfe/
    this.myOtherMethod = function myOtherMethod() {
      alert( 'my other method' );
    };

  }

  // expose access to the constructor
  window.MyModule = MyModule;

} )( window );

// example usage
var myModule = new MyModule();
myModule.myMethod(); // alerts "my method"
myModule.myOtherMethod(); // alerts "my other method"

例子二

var MyModule = ( function( window, undefined ) {

  // this object is used to store private variables and methods across multiple instantiations
  var privates = {};

  function MyModule() {

    this.myMethod = function myMethod() {
      alert( 'my method' );
    };

    this.myOtherMethod = function myOtherMethod() {
      alert( 'my other method' );
    };

  }

  return MyModule;

} )( window );

// example usage
var myMod = new MyModule();
myMod.myMethod(); // alerts "my method"
myMod.myOtherMethod(); // alerts "my other method"