jQuery 速查表
1. Selectors
2. Attribute / Css
3. Manipulation
4. Traversing
过滤器
Miscellaneous(各种各样的，混杂的) Traversing(遍历)
.end()
End the most recent filtering operation in the current chain and return the set of matched elements to its previous state. (结束当前过滤器调用链，返回上一个匹配的元素集)
$( "ul.first" )
.find( ".foo" )
.css( "background-color", "red" )
.end()
.find( ".bar" )
.css( "background-color", "green" );