JQuery

* any element
E an element of type E
E:nth-child(n) an E element, the n-th child of its parent
E:first-child an E element, first child of its parent
E:last-child an E element, last child of its parent
E:only-child an E element, only child of its parent
E:empty an E element that has no children (including text nodes)
E:enabled a user interface element E which is not disabled
E:disabled a user interface element E which is disabled
E:checked a user interface element E which is checked (for instance a radio-button or checkbox)
E:selected a user interface element E which is selected (one or more option elements inside a select) - not in the CSS spec, but nonetheless supported by jQuery
E.warning an E element whose class is "warning"
E#myid an E element with ID equal to "myid". (Will only match, at most, one element.)
E:not(s) an E element that does not match simple selector s
E F an F element descendant of an E element
E > F an F element child of an E element
E + F an F element immediately preceded by an E element
E ~ F an F element preceded by an E element
E,F,G select all E elements, F elements, and G elements

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]")

See also