如果想做一个可折叠的菜单要怎么做.

Question

    ┌Document -HTMLDocument
Node├CharacterData┌Text
    │      └Comment
    ├Element -HTMLElement┌HTMLHeadElement
    └Attr                ├HTMLBodyElement
  ├HTMLTitleElement
      ├HTMLParagraphElement
  ├HTMLInputElement
  ├HTMLTableElement
  ├...etc.比如有个小"+"号,点开之后变成"-"号,这时才显示出下一级菜单.......

Answer 1

<ur>
   <li>
   </li>
<ur>
这个吧

Answer 2

http://www.zzsky.cn/build/content/1578.htm
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