Jquery retrieves objects

1,  Some core methods of jquery  
$ ("Element" ). Length; 'number of elements, which is an attribute $ ( "Element" ). Size (); 'is also the number of elements, but parentheses are a method $ ( "Element" ). Get (); 'a set of elements in the page, stored in arrays $ ( "Element" ). Get (INDEX); 'has the same function as above. index indicates the nth element, and the subscript of the array $ ( "Element" ). Get (). Reverse (); 'to get the direction of the array $ ( "Element1"). Index ($ ("element2" ); 'Element 2's index value in element 1 is...
  2  , Basic object acquisition (note that all the objects obtained here are jquery objects instead of DOM objects, but they can be converted)$ ( "*" ) 'Indicates getting all objects, but I have never used it like this $ ( "# XXX") 'Get ID = Element Object of XXX (ID can be the tag ID or CSS style ID) commonly used $ ( "Input [name = 'username']") obtain the name = 'username' in the input tag'Commonly used element objects $ ( ". ABC ")' Get the style class name. ABC element object commonly used $ ("Div ") ' The tag selector Selects all DIV elements commonly used $ ( "# A,. B, span ")' It indicates that the element whose ID is a and that uses Class B and all span elements $ ("# A. B P ") 'Id is a and all P elements in B style are used.

 3. Hierarchical Element Acquisition 
 $("Element1 element2 element3...") 'the front parent level is followed by a subset 
 $ ("Div> P") 'gets all P elements under the div. 
 $ ("Div + P") the first P element after the DIV Element 
 $ ("Div ~ P ") All P elements behind 'div
 
 4. Simple Object acquisition 
 $ ("Element: First") 'First element of a certain element in the HTML page 
$ ("Element: Last") the last element of a certain element in the HTML page 
 $ ("Element: Not (selector)") 'removes all elements that match the given selector, for example: $ ("input: Not (: checked )") indicates Selecting All unselected check boxes. 
 $ ("Element: Even") 'returns an even number of rows. 
 $ ("Element: odd") 'returns an odd number of rows. 
 $ ("Element: eq (INDEX)") 'gets a given index value 
 $ ("Element: GT (INDEX)") All elements after obtaining the element of the given index value 
 $ ("Element: Lt (INDEX)") 'gets all elements before the element with the given index value 

 5. Get content objects and object visibility 
 $ ("Element: Contains (text)") 'indicates whether the element contains text content. 
 $ ('Element: empty ") 'gets 
$ ("Element: partnt") 'obtains 
 $ ("Element: Has (selector)") 'indicates whether an element exists. For example, $ ("P: Has (SPAN)") indicates all P elements containing the span element. 
 $ ("Element: hidden") 'select all visible elements 
 $ ("Element: visible") 'select all invisible elements
 
 6. Other Object acquisition methods 
 $ ("Element [ID]") 'all elements with the ID attribute 
 $ ("Element [attribute = youlika]" 'obtains all elements whose attributes are youlika. 
 $ ("Element [attribute! = Youlika] "'Get all elements whose property is not youlika 
 $ ("Element [attribute ^ = youlika]" 'obtains all elements whose attributes start with not youlika. 
 $ ("Element [attribute $ = youlika]" 'obtains all elements whose attributes are not the end of youlika. 
$ ("Element [attribute * = youlika]" 'obtains all elements whose attributes start with youlika. 
 $ ("Element [selector1] [selector2] [...] ") 'matches the property selector. For example, $ (" input [ID] [name] [value = youlika] ") indicates that the input element with ID, name, and value is youlika is obtained.
 
 7. Obtain sub-elements 
 $ ("Element: Nth-child (INDEX)") 'select the nth element under the parent level 
 $ ("Element: Nth-child (even)") 'select an even number under the parent level 
 $ ("Element: Nth-child (ODD)") 'select the odd number under the parent level 
 $ ("Element: Nth-child (3N + 1)") 'expression 
 $ ("Element: First-Child") 'selects the first child element under the parent level. 
 $ ("Element: Last-Child") 'selects the last child element under the parent level. 
 $ ("Element: Only-Child") 'matches a unique child element under the parent level. For example, if dt is unique in the DL list, DT is selected.
 
 8. Get form objects 
 $ (: Input) // query all input elements, including the drop-down list, text field, single-statement, and check box. 
 $ (: Text) // match all single-row text boxes 
 $ (: Password) // match all password boxes 
 $ (: Radio) // match all radio buttons 
 $ (: Checkbox) // match all check boxes 
 $ (: Submit) // match all the submit buttons 
 $ (: Image) // match all image fields, for example, <input type = "image"/> 
 $ (: Reset) // match all reset buttons 
 $ (: Button) // match all buttons 
 $ (: File) // match all file upload Domains 
 $ (: Hidden) // matches all the invisible elements or elements whose type is hidden. 
$ (: Enabled) // match all available input elements. For example, radio: enabled indicates matching all available single-choice buttons. 
 $ (: Disabled) // matches all the unavailable input elements, which act in the opposite way. 
 $ (: Checked) // match all checked check box Elements 
 $ (: Selected) // match all the drop-down lists
 
 9. Setting and removing element attributes 
 $ ("Element"). ATTR (name) 'gets the first matching property value, for example, $ ("IMG"). ATTR ("src ") 
 $ ("Element". ATTR (Key, value) ") 'specifies the attribute of an element. 
 $ ("Element". ATTR ({key: value, key1: value,...}) 'sets multiple attributes for an element at a time. 
 $ ("Element"). ATTR (Key, function) 'sets a calculated attribute value for all matching elements. 
 $ ("Element"). removeattr (name) // remove an attribute