面试题：JQuery有几种选择器?

很多种，大概归纳为9种。
(1)基本
#id
element
.class
*
selector1,selector2,selectorN 

(2)层次选择器：
ancestor descendant
parent > child
prev + next
prev ~ siblings 

(3)基本过滤器选择器
:first
:last
:not
:even
:odd
:eq
:gt
:lt
:header
:animated 

(4)内容过滤器选择器
:contains
:empty
:has
:parent 

(5)可见性过滤器选择器
:hidden
:visible 

(6)属性过滤器选择器
[attribute]
[attribute=value]
[attribute!=value]
[attribute^=value]
[attribute$=value]
[attribute*=value]
[attrSel1][attrSel2][attrSelN] 

(7)子元素过滤器选择器
:nth-child
:first-child
:last-child
:only-child 

(8)表单选择器
:input
:text
:password
:radio
:checkbox
:submit
:image
:reset
:button
:file
:hidden 

(9)表单过滤器选择器
:enabled
:disabled
:checked
:selected