Object Creation

　　Although using the object constructor or an object literal are convenient ways to create single objects, there is an obvious downside: creating multiple objects with the same interface requires a lot of code duplication. To solve this problem, developers began using a variation of the factory pattern.

The Factory Pattern

　　With no way to define classes in ECMAScript, developers created functions to encapsulate the creation of objects with specific interfaces, such as in this example:

 1 function createPerson(name, age, job){
 2     var o = new Object();
 3     o.name = name;
 4     o.age = age;
 5     o.job = job;
 6     o.sayName = function(){
 7         alert(this.name);
 8     };
 9     return o; 
10 }
11 
12 var person1 = new Person("Nicholas", 29, "Software Engineer");
13 
14 var person2 = new Person("Greg", 27, "Doctor");

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　　Though this solved the problem of creating multiple similar objects, the factory pattern didn‘t address the issue of object identification(what type of object an object is). 

Object Creation

原文：http://www.cnblogs.com/linxd/p/4488826.html