An interesting analysis of web technologies

[MikeGale]

Sane analyses of the web based on facts seem to be getting rare.

I found one today that is better than most. I don't agree with all the conclusions, but the depth and good analysis impressed me.

This is a video and it goes on for a long time, so it's not everbody's cup of tea.

I recommend Doug Crockford's talk (which seems to be about Ajax, but much of it is about HTML, CSS and how they came to be so) http://developer.yahoo.com/yui/theater/video.php?v=crockonjs-4

[MikeGale]

The first bit of the presentation is not relevant. I found you can skip it by moving the slider in the flash player. Alternately stop the video and read the text, which is a transcript of the talk.

It's interesting how he weaves it all together from SGML to AJAX. There's a few irreverent comments on the way, which are worth thinking about, even those you don't agree with.

[Lou]

Mike thanks for the link. The history of why we are in the mess we are in was interesting. Some I have lived through, some I had forgotten about.

You are right he does through in an opinion or two along the way. I didn't mouse over the video and see the slider until near the end. Oh well

Lou

[Albert Wiersch]

Mike, thanks from me to. I just finished watching the entire presentation. That was indeed interesting, especially the history (I didn't skip it).

He doesn't seem to like the W3C too much.

I thought it was interesting that he says CSS is awful and based on the "unhealthy separation of structure and presentation". Others see that as a benefit. While he says CSS works to an extent, I wonder what his idea is of something better. Of course now that CSS is widely used I'm sure it's here to stay.

[MikeGale]

I looked at some of his other presentations. He takes a broad view which I like. He leaves out details and sometimes gets them wrong but his take on things is much better than just about everything else I've seen.

I think his irreverent attitude is a health antidote to the blind acceptance I often see!

I often agree with him:
1) The different naming of CSS properties in CSS and in Javascript is plain nutty.
2) HTML is missing a lot and HTML (the standard formerly known as HTML 5) is not fixing some of them.
3) Xanadu had some great ideas, which aren't here yet.
4) Some features of the Javascript language should be removed. (I see he upset the apple cart on ECMAscript 4, seems to have driven a lot of ECMAscript 5, which looks like an improvement.) Javascript is an astonishingly good design, though contaminated by a few bad things, like the Java date/time import, number weirdness...

He is an activist, so he has an agenda. (Like he wants to see HTTP replaced with something more appropriate. I agree.)

Despite the problems I think, like you, CSS has proved very useful, and will stay. The separation works for me. (Though human readability could be better.) From his comments I wonder how much hands on coding of HTML and CSS he has done. If he hasn't that would explain some of his comments.

[Albert Wiersch]

Because of document.write, where you put a script tag within a file can have a huge impact on page loading time. The recommendation is to place the script source tags as close to the bottom of the body as you can. The reason for that is that when a script tag is loading, the browser has to be pessimistic about what damage that script might do to the document it hasn't parsed yet. It will stop downloading of assets, it will stop looking for images it can load, and not do anything. Basically, everything gets frozen until the HTTP request to get the script tag completes and the script runs to completion. At that time, it can then resume HTML parsing. If you have several script tags in a row, you're going to go serial stop request, response, execute, stop request, response. So it slows everything down. If you put it at the bottom then there's a chance for all of the images that are in the document to be loading concurrently, so you just get much faster performance.

I was considering adding a tip to place scripts close the the bottom of the body... but I'm curious, has anyone experienced that this really makes a difference? Does anyone think this is a good (useful) tip to add to CSE HTML Validator when "script" is used? Thanks!

[MikeGale]

This is an area where I disagree (as a blanket suggestion).

Like all things web it depends on what you're doing.

Where you're designing your own content, HTML, images, script, back end services I think you can often ensure that script at the top is a good idea. (There was a debate about this many years ago. I can't recall the details, but it left me inclined to script at the top.)

With image heavy pages, and a lot of third party scripts (which you don't bother to integrate into a few coherent script files) the advice might have more importance.

I'd love to see an analyis of this. Different browsers, different page designs and philosophies. That would give a more rounded view. On top of that what impact do already loaded scripts have? Presumably the first page has the load and later pages don't...

I'd love to see a scientific evaluation. In the absence of that I'd make sure the suggestion is compatible with the range of what happens.

(I personally like to see developers encouraged to do things a bit smarter and simpler, especially in this age where script is often misused. There is a site I visit often. It was redesigned recently. I think the scripts are loaded late, then they do a lot of work. After the page is loaded I go away and do something else until the code has all run (then navigation works!!) If that's what's going on, late script loading, it's a prime example of abuse. I did have a look at the code while I was discussing the site with the creators, it was too much to get my mind around in the time available!)

[Albert Wiersch]

Thanks Mike. Your message confirms my suspicion that it's not a very helpful or useful tip in the general case, or I suspect I would have read or heard more about the advantages of placing scripts near the bottom of the body... but if anyone has more to say about this, then please share.