$ (""tagname "")
2. Get elements by ID
$(""#id_name " ")
3. Get the element by the class name.
$ ("".Class name "")
4. Get multiple elements at once.
$ (""element name, element name, element name ... "")
5. Obtain elements by specifying hierarchical relationships.
$ (""ancestors and descendants "")
$ (""parent > child "")
$ (before ""+after "")
$ (""Brother ~ Brother "")
6. Get the element according to its attribute value.
[attribute]
[Attribute = Value]
[attribute! = value]
[Attribute = Value]
[Attribute $ = Value]
[Attribute * = Value] "