Learning from Twitter
ejohn.org
ejohn.org
However, I'm disappointed in how twitter, or more accurately, Dustin Diaz handled this situation. They identified some performance issues. Narrowed it down to a jQuery version but just left it there.
jQuery is open source so they could have done some investigating on their own and tried to narrow down what changed in that selector. Especially since this change was blogged about (as mentioned by John).
Not to mention various people helped out twitter by finding some pretty obvious flaws and made suggestions. Twitter has a lot of resources and I'm assuming a lot of talented Javascript engineers. This is a situation where they could have used their resources to contribute to an open source project instead of the other way around.
It's not hard to pinpoint the exact line of code that is causing the slow down and come to a conclusion. This could have easily been fixed without reverting to jQuery 1.4.2 and risk breaking other things in the process (assuming they upgraded to 1.4.4 for a good reason).
On top of that it was their own code which led to the slowdown. Passing the blame to jQuery seems wrong when it was their own mistake to disregard best practices.
Here is where Twitter failed:
1) Need better testing when updating a version of the library.
2) Need to understand what the library you are using is doing and how to avoid performance bottlenecks.
Basic stuff.
It would really help us out if people could slip our pre-release versions into their test environments. There's a 1.5 beta available now (http://blog.jquery.com/2011/01/14/jquery-1-5-beta-1-released...). Don't wait several months to try it the way Twitter waited on 1.4.4, or we may ship 1.5 with some bug that impacts your site.
We happened to use http://www.infinite-scroll.com, which also bind to window scroll event as well. Let's see how it goes.
Thank you so much for all the hard work that goes into jQuery.
// execute callback only after a pause in user input; the function returned
// can be used to handle an event type that tightly repeats (such as typing
// or scrolling events); it will execute the callback only if the given timout
// period has passed since the last time the same event fired
function createOnPause(callback, timeout, _this) {
return function(e) {
var _that = this;
if (arguments.callee.timer)
clearTimeout(arguments.callee.timer);
arguments.callee.timer = setTimeout(function() {
callback.call(_this || _that, e);
}, timeout);
}
}
document.addEventListener('scroll', createOnPause(function(e) {
// do something interesting here
}, 1500, this), false);
I've been working on jQuery full-time now for about 1.5 years (sponsored by my employer, Mozilla). Prior to that I worked on jQuery in my spare time for about 4 years while doing other things (I was in college, then in Y Combinator - Summer 2006, and then worked for Mozilla as a JavaScript Evangelist).
I've managed to pigeon-hole myself into the position of a JavaScript framework maintainer rather solidly (for better or worse).
That being said I really enjoy what I do and have trouble thinking of something that I would rather do as my day job. Being able to work on a piece of code that I've largely written from scratch and promote it to a community of eager users is my dream. I've often thought about making a leap into something else but struggle to think of something that would hold my interest as deeply.
I'm largely not interested in starting or joining a business. For whatever reason I frequently find that attaching a profit motive to work largely impedes my ability to be happy and seems to run contrary to my overall goals (educating people, giving good tools to developers -- and providing both to anyone and everyone, no restriction).
Perhaps I'll find some interesting project some day that will open the financial floodgates (or perhaps I'll enter a situation -- such as having children -- that will necessitate me earning more than I do now) but I'm quite content now where I am, doing what I'm doing.
All this being said, I'm constantly looking at and exploring new things. At the moment though most of that is outside the realm of JavaScript, or even computers, and mostly relating to art. It's unclear to me if that's something that'll hold my long-term interest (although it has for the past few years) but we shall see.
It was around that time that Twitter came out (which we poo-pooed due to its lack of features). It wasn't until a few months later (and after we had run out of money and had to get real jobs) that we realized that Twitter was a much better solution for what we had wanted to achieve.
It's not a loss, though. We had a great experience and all ended up getting great jobs doing things that we love. I went on to work at Mozilla. Julia went on to work at a few startups and is now starting a pretty cool video dating site: Inlu.st, and Josh is working at Blue State Digital (he did work for the Obama campaign).
For reference, the clip from The Office: http://www.youtube.com/watch?v=ytc9-wGCHW0
However where my real passion lies is in art history. Specifically I've been spending a considerable amount of time studying, researching, and collecting Ukiyo-e (Edo-era Japanese woodblock prints). It's an incredible art form and to study it is to study the complete culture of Japan in the 17th to 19th century. I'm lucky as I live less than a mile away from the Harvard art library and have a friend that works as a librarian there - so I end up spending a lot of time checking out research material, studying, and learning. (For example, right now I'm reading a book on Kabuki theater and its relevance within the context of Ukiyo-e.)
I've started to write a little bit about the art form (as my time allows, which is kind of challenging) here: http://ukiyoe.tumblr.com/
I also run the Ukiyo-e sub-Reddit: http://www.reddit.com/r/ukiyoe/
I hope to do more research and writing in this area during the upcoming months, time permitting of course!
This is true of just about any API. Nobody blames the API when their ORM layer generates a massive SQL query based on complex query input. Understanding the performance characteristics of the 'backend' is assumed.
$FOO in php is cheap.
$('FOO') in jquery is expensive.
They're doing what they think is best, so I don't blame them. I blame jquery for making it look cheap.
I can't offhand think of a single example where they've improved my experience. (With the exception of things like Google Maps where the JS is an important part of the user interface.) When, for example, a menu or picture animates open instead of appearing instantly, at best I feel mild irritation.
Maybe I'm just a cumudgeon.
Scrolling did indirectly change the DOM as you load more tweets when you scroll. But the point here is that the actual scrolling is not changing the DOM, the append is, and that's probably when you should update your query cache.