jQuery doesn't cache elements for you. If you've made a selection that you might need to make again, you should save the selection in a variable rather than making the selection repeatedly.

Noncompliant Code Example

$( "p" ).hide();
$( "p" ).show();

Compliant Solution

var paragraph = $( "p" );

paragraph.hide();
paragraph.show();

Exception

Stored selections are not updated when the DOM changes. Since variables may need to updated this rule ignores selections that are repeated during an assignment.

var paragraph = $("p");

// ...

paragraph = $("p");