Comments on: jQuery Performance Rules

By: Mads Jensen

Mads Jensen — Fri, 29 Jan 2010 19:09:28 +0000

Good learning experience on getting my jquery scripts perform even better! Good job!

By: buy r4 ds

buy r4 ds — Sat, 23 Jan 2010 16:26:06 +0000

Nice catch Joseph – I had meant that to use a jQuery selector for that ID. But that’s news to me on being able to pass document.getElementById(‘blah’) to the jQuery context, seems like that could be useful. Do you have any idea whether it is better performance-wise to do that rather than $(’blah’).find(’blah’)?

By: Paul Irish

Paul Irish — Fri, 15 Jan 2010 15:49:29 +0000

Great rules Dave, these have helped a lot of developers.
I have some more stuff about selector optimization and some other goodies in my talk on jQuery Anti-Patterns for Performance:
http://paulirish.com/perf

By: ArtzStudio

ArtzStudio — Sat, 05 Dec 2009 01:33:05 +0000

@Erik – thanks, I can’t believe I did that.

By: zsiswick

zsiswick — Fri, 04 Dec 2009 23:03:13 +0000

Thank you for the thorough article. I have had performance concerns with using jQuery on a larger production website, and I will be utilizing some of the strategies you outlined moving forward. Adding bookmark.

By: Erik Kallen

Erik Kallen — Fri, 27 Nov 2009 12:00:15 +0000

The article is good, but your example for binding to parent is bad. The focus event is one of those that do NOT bubble. Replace it with another event that does.

By: ArtzStudio

ArtzStudio — Sat, 14 Nov 2009 15:46:03 +0000

@Bart – They’re actually the same thing when you dig into the code, so I think it comes down to your preference. A fun thing to try is using Firebug and its Breakpoint feature, so you can peak under the hood at what jQuery is doing. It’s sometimes enlightening.

By: Matthew Sweet

Matthew Sweet — Thu, 05 Nov 2009 21:59:53 +0000

‘nother tip, not related to any of the rules.

If you’re enumerating over a an array, use a natve for/in loop, not $.each. It’s must faster.

By: Robert

Robert — Sat, 31 Oct 2009 17:27:29 +0000

Thanks for the great post. Was exactly what I was looking for.

By: Bart

Bart — Mon, 05 Oct 2009 23:48:45 +0000

Thanks for some nice tips.

Regarding the subqueries, I wonder which way is faster:
var $traffic_light = $(’#traffic_light’),

$red = $traffic_light.find(’.red’)
or
$red = $(’.red’, $traffic_light)

I usually use the second one, with context.