Learning javascript must subscribe to a programmer's Blog 30

Reprinted: http://lu.9efish.com/blog/%E5%AD%A6%E4%B9%A0javascript%E5%BF%85%E9%A1%BB%E8%AE%A2%E9%98%8530 % E4% B8% AA% E7 % A8% 8B% E5% BA% 8F% E5% 91% 98% E7% 9A% 84blog

Reproduced in: https: //www.cnblogs.com/dotLive/archive/2011/02/10/1951005.html