cheat sheets.

(from jQuery in Action)

Basic CSS selectors

*    - any element
E    - elements with tag E
E F  - elements with tag F that are descendants of E
E>F  - elements with tag F that are direct children of E
E+F  - elements F immediately preceded by sibling E
E~F  - elements F preceded by any sibling E
E:has(F) - elements E that have at least one decedent with tag F
E.C  - elements with class name C. omitting E is the same as *.C
E#I  - elements E with id I. omitting E is the same as *#I
E[A] - elements with attribute A of any value
E[A=V]  - elements with attribute A whose value is exactly V
E[A^=V] - elements with attribute A whose value begins with V
E[A$=V] - elements with attribute A whose value ends with V
E[A*=V] - elements with attribute A whose value contains V

Advanced positional selectors

:first - first match of the page
:last  - last match of the page
:first-child - first child element
:last-child - last child element
:only-child - elements that have no siblings
:nth-child(n) - nth child element
:nth-child(even|odd) - even or odd children
:nth-child(Xn+Y) - nth child element computed by formula
:even and :odd - even and odd elements page wide
:eq(n) - the nth matching element
:gt(n) - elements after (and excluding) nth matching element
:lt(n) - elements before (and excluding) nth matching element

Custom selectors

:animated - elements that are under animated control
:button - any button
:checkbox - only check box elements
:checked - check boxes or radio buttons that are checked
:contains(foo) - elements containing text foo
:disabled - form elements that are disabled
:enabled - form elements that are enabled
:file - selects all file elements
:header - all elements h1..h6
:hidden - elements that are hidden
:image - form images
:input - form elements
:not(filter) - negates the specified filter
:parent - elements that have children
:password - password elements
:radio - radio elements
:reset - reset buttons
:selected - option elements that are selected
:submit - submit buttons
:text - text elements (input[type=text])
:visible - elements that are visible

Hide all Paragraph elements that contain a class attribute:

 $("p[class]").hide();

Show the first paragraph on the page:

 $("p:eq(0)").show();

Hide all divs that are currently showing:

 $("div:visible").hide();

Get all list items that are children of an unordered list:

 $("ul/li")
 /* valid too: $("ul > li") */

Get all Paragraphs, with a class of 'foo', that have a link in them:

 $("p.foo[a]");

Get list item that contains link with "Register" text inside:

 $("li[a:contains('Register')]");

Get the input field's value with the name of 'bar':

 $("input[@name=bar]").val();

All checked radio buttons:

 $("input[@type=radio][@checked]")

Disable then re-enable an element:

 $("#my").attr('disabled',true);
 $("#my").removeAttr('disabled');

Add/Remove CSS style:

 $("#my").addClass("highlight").removeClass("arrr");

Highlight in yellow a newly updated element for 3 seconds:

 $("#my").effect('highlight', {color: 'Yellow'}, 3000);

Make an Ajax call:

 $.ajax({
   type : 'POST',
   url  : '/app/action',
   data : { attribute1: 'value1', 
            attribute2: 'value2' },
   dataType: 'json',
   async : false,
   success: function(result) {
      /* use json result.attribute3, ...  */
   }
 });

 $.get('/app/action', function(data) { ... });

Generate new HTML DOM nodes:

  $("<div>This is new</div>");
  $("<div></div>");
  $("<div>");

Setting Element Content

  $("<li>This is new</li>").appendTo("#list");