Question

Is there any benefit to performance when I do the following in Mootools (or any framework, really)?:

var elem = $('#elemId');    
elem.addClass('someClass');        
elem.set('some attribute', 'some value');

etc, etc. Basically, I’m updating certain elements a lot on the DOM and I was wondering if creating a variable in memory and using that when needed was better than:

$('#elemId').addClass('someClass');    
$('#elemId').set('some attribute', 'some value');

The changes to $('#elemId') are all over the place, in various different functions.

Answer 1

Spencer ,

This is called caching and it is one of the best practices.

when you say

$('#elemId');

It will go and query the DOM everytime , so if you say

var elem = $('#elemId');

elem acts as a cache element and improves performance a lot.

This is manly useful in IE as it has memory leaks promblem and all

ready this document which is really good

http://net.tutsplus.com/tutorials/javascript-ajax/14-helpful-jquery-tricks-notes-and-best-practices/