Deferred

http://blog.allenm.me/2012/01/jquery_deferred_promise_method/

http://www.ruanyifeng.com/blog/2011/08/a_detailed_explanation_of_jquery_deferred_object.html

http://www.07net01.com/zhishi/467662.html

jquery series

http://blog.csdn.net/yanyan19880509/article/details/7339900