JavaScript 设计模式学习 Singleton

/* Basic Singleton. */ 
var Singleton = { 
attribute1: true, 
attribute2: 10, 
method1: function() { 
}, 
method2: function(arg) { 
} 
}; 
单件模式最主要的用途之一就是命名空间： 
/* GiantCorp namespace. */ 
var GiantCorp = {}; 
GiantCorp.Common = { 
// A singleton with common methods used by all objects and modules. 
}; 
GiantCorp.ErrorCodes = { 
// An object literal used to store data. 
}; 
GiantCorp.PageHandler = { 
// A singleton with page specific methods and attributes. 
}; 
利用闭包在单件模式中实现私有方法和私有变量： 
GiantCorp.DataParser = (function() { 
// Private attributes. 
var whitespaceRegex = /\s+/; 
// Private methods. 
function stripWhitespace(str) { 
return str.replace(whitespaceRegex, ''); 
} 
function stringSplit(str, delimiter) { 
return str.split(delimiter); 
} 
// Everything returned in the object literal is public, but can access the 
// members in the closure created above. 
return { 
// Public method. 
stringToArray: function(str, delimiter, stripWS) { 
if(stripWS) { 
str = stripWhitespace(str); 
} 
var outputArray = stringSplit(str, delimiter); 
return outputArray; 
} 
}; 
})(); // Invoke the function and assign the returned object literal to 
// GiantCorp.DataParser. 
实现Lazy Instantiation 单件模式： 
MyNamespace.Singleton = (function() { 
var uniqueInstance; // Private attribute that holds the single instance. 
function constructor() { // All of the normal singleton code goes here. 
... 
} 
return { 
getInstance: function() { 
if(!uniqueInstance) { // Instantiate only if the instance doesn't exist. 
uniqueInstance = constructor(); 
} 
return uniqueInstance; 
} 
} 
})(); 
MyNamespace.Singleton.getInstance().publicMethod1();