jquery selectors speed

Question

Which of these two is better/faster?

var a = $('.listItem', $('#myList'));

vs

var a = $('#myList .listItem');

Answer 1

First of all, you're doing it wrong in a weird way. It should be:

var a = $('.listItem', '#myList');

And according to Resig, the find() method has proven to be quickest in most cases:

var a = $("#myList").find(".listItem");

Answer 2

The only real way to know is to profile them, that is really the only answer that can be given to the question. There will be a slight performance hit with the first since context works best when it is an element and not a jQuery object.