How can I detect if a selector returns null?

Question

What is the best way to detect if a jQuery-selector returns an empty object. If you do:

alert($(\'#notAnElement\'));

you get [object Object

Answer 1

This is in the JQuery documentation:

http://learn.jquery.com/using-jquery-core/faq/how-do-i-test-whether-an-element-exists/

  alert( $( "#notAnElement" ).length ? 'Not null' : 'Null' );