标签：
classList http://www.zhangxinxu.com/wordpress/?p=3483
offsettop等 http://www.jb51.net/css/22675.html
http://www.cnblogs.com/trlanfeng/archive/2012/11/04/2753280.html
javascript 01
原文地址：http://www.cnblogs.com/swii/p/5496612.html
