F.Y.I.
http://www.ruanyifeng.com/blog/2009/08/learning_javascript_closures.html
闭包的工作原理：
http://www.frontopen.com/1702.html
Javascript内存分配：
http://www.cnblogs.com/kycool/archive/2011/11/30/2268653.html
栈内存or堆内存：
http://www.tuicool.com/articles/m2queq
闭包：
http://www.cnblogs.com/TomXu/archive/2012/01/31/2330252.html