jquery deferred

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

http://www.cnblogs.com/CodeGuy/archive/2013/05/24/3096601.html

http://blog.mixu.net/2011/02/01/understanding-the-node-js-event-loop/

http://blog.csdn.net/yanghua_kobe/article/details/12145537

http://blog.csdn.net/flowingflying/article/details/7842144

http://book.51cto.com/art/201303/385824.htm