Deferring scripts for faster rendering
So it turns out one can defer scripts, meaning give the browser a hint that a script will not mess up with the page right now, so it won't affect the rendering and can be delayed for later. This could give you increased performance during the initial page load and rendering, since you're giving the browser a clearance to temporarily skip this script and continue with the other magic it's doing.
The syntax is simple, just add defer attribute to the script tag and (to be XHTML compliant, give it a) "defer" value. Like this:
<script type="text/javascript" defer="defer"> // deferred … </script> <script type="text/javascript" src="defer.js" defer="defer"> </script>
Believe it or not, the defer attribute, which originated from MS, is now a part of the standard XHTML, as well as HTML4.01 strict and is not supported by FireFox.
I put up a little demo, if you want to see it in action. In my demo, if you check it with FF (all defers ignored) you'll get:
With the defers, in IE, you get:
Have in mind that there's not guarantee it will always happen like this. If, for example, an external non-deferred script is taking a while to download, a deferred one might get processed it it's ready. So you cannot rely on this, you can merely instruct the browser: "Hey, dude, this is a low priority, do the rendering first, the best you can…"
October 24th, 2006 at 10:31 am
Now, how often does a person see that happen? That is interesting. Sometimes, I wonder with all of our rules — and, of course, the complaining because MS goes its own direction — what type of innovation we are discouraging. In this case, from the sounds of it, MS did the right thing. I don't think we will ever figure it all out.
October 24th, 2006 at 11:00 am
Oh, yes, MS has done a lot of innovation, I mean take XMLHttpRequest, the thing that powers all the AJAX apps, it's also from MS. All the complaining (web-related) originates from thefact that IE6 was abandoned by MS for some reason. Seems like MS didn't do anything in the past 5 or so years to solve obvious reported issues with the browser. It's normal that every browser will have issues, but 5 years, which in internet time is … who knows. Looks like IE7 is the New Hope, though
October 24th, 2006 at 11:48 am
Wow. It is very good to hear some positive MS news. No matter how anyone feels about MS, the truth is this: they ain't goin nowhere! So, I am happy to hear that you see them as contributors and innovators still. They sure were the revolutionary ones 12-15 years ago. Did some amazing stuff to the industry back then. I was a proud MS developer back then.
Past few years, they have done things with ADS and their high-end tools and site licensing "threats" that I think are not so cool, so, I will be slow to come back, but, I am encouraged to hear you say these things.