Using :even or filter(":even") in jQuery

Question

I am reading the jQuery API, about even selector, jQuery recommend we select a list of elements use pure CSS Selector and then use filter(":even") for better performance. But I think jQuery optimized for their :even selector too. When I used any selector, it gave me the same result with the same time. Will it have different only when we have more than 1 million of elements? Could someone please explain how the :even selector work and why use filter(":even") is better?

Thanks, Tho Vo

Answer 1

Why not test it? http://jsperf.com/even-selector

If you're looking for something fast, use :nth-child(even), as it's a native selector and can be fed into document.querySelectorAll. :even is a jQuery-specific pseudo-selector and forces jQuery to traverse the DOM using JavaScript, which will almost always be slower than document.querySelector.