Question

Imagine this simplified markup:

<div id="header">
   <!-- Other things.... -->
   <div id="detail">

   </div>
</div>

and assume you already have this code:

var $hdr = $("#header");

Is there any speed difference for jQuery to lookup “detail” this way:

var $detail = $("#detail", $hdr);

vs

var $detail = $("#detail");

Since detail is being looked up by ID?

Answer 1

No, you don’t have to do that. Since id is unique in a document no need to add any other optimization.

I would go with

var $detail = $("#detail");