jQuery Asynchronous
http://www.ruanyifeng.com/blog/2011/08/a_detailed_explanation_of_jquery_deferred_object.html
http://www.cnblogs.com/snandy/archive/2012/12/19/2812935.html
http://www.ruanyifeng.com/blog/2012/12/asynchronous%EF%BC%BFjavascript.html
http://www.cnblogs.com/snandy/archive/2012/11/15/2770237.html
http://www.cnblogs.com/snandy/archive/2012/11/15/2771128.html
http://www.cnblogs.com/evilyang/archive/2012/01/11/2319541.html
出处:http://cnblogs.com/daishuguang