js知识点-立即执行函数表达式

http://www.imooc.com/qadetail/70976
http://openxtiger.iteye.com/blog/1893378
https://my.oschina.net/sfm/blog/33197
https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Function/apply
https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Object/toString
http://www.cnblogs.com/wyaocn/p/5796142.html
http://www.cnblogs.com/wyaocn/p/5795991.html
http://bbs.9ria.com/thread-113177-1-1.html
https://segmentfault.com/a/1190000003046071
https://www.zhihu.com/question/32175033
http://suqing.iteye.com/blog/1981591/
http://www.bubuko.com/infodetail-357253.html
http://www.cnblogs.com/jiangtian/p/6226685.html
https://juejin.im/entry/5704e12771cfe4005dc85868