Question

Probably this will not result in any noticable performance difference, but I was just interested. If I am removing a class on a list of elements using jQuery, is it better practice or performance to include the class in the selector?

So either include it:

$('#myList li.classToRemove').removeClass('classToRemove');

or don’t include it:

$('#myList li').removeClass('classToRemove');

So basically is there any difference to narrowing the list in the selector and in the removeClass method.

Answer 1

Selectors are matched backwards (last to first), meaning it will first find “all elements with “classToRemove” which are also “li” which are also children of “#mylist” “.

It’s done that way to narrow down the list as much as possible, as soon as possible.

Therefore, you should go with

$('#myList li.classToRemove').removeClass('classToRemove');

Less items to match means a faster, more efficient script.