Busy — Thu, 21 Nov 2002 04:01:32 +0000

I don't think preload scripts affect the loading order, if anything it probably goes images - backgrounds - preload
File size doesnt seem to matter either.

and if CSS is before images (would have to be) are the css images (backgrounds) faster or slower than HTML backgrounds.

using a 5x5 pixel background image is slower than using a 25x25 image, smaller file size but bigger area it has to cover

I think at the end of the day as long as all the images are small in size it shouldnt really matter.

SW Reynolds — Thu, 21 Nov 2002 01:17:21 +0000

From Busy: "I believe the images are loaded before the backgrounds are."

So if a person wanted the small background to quickly load and therefore be viewable before some of the larger graphics (which may be lower on the page, below the scroll line), would it make sense to use a js pre-load image script just for the background file?

If as imaputz says the js loads early in the process, perhaps that would be one way to maintain a bit of control over the order??

Mark Hensler — Thu, 21 Nov 2002 00:59:47 +0000

Apache logs are appended after a connection closes. When I download a large file from my cousin's server (Win2K, Apache 1.3.x), he doesn't see me in the log until after the file download is done.

imaputz — Thu, 21 Nov 2002 00:25:47 +0000

I looked into this sometime ago. My access logs show a nice pattern regarding how browsers request files. One item I noticed is that browser XYZ requests files in the same order as browser ABC. It's the protocol where the request order differs (HTTP 1.0 vs HTTP 1.1).

For HTTP 1.1 request order was typically: HTML, CSS, JS, IMAGES

For HTTP 1.0 request order was typically: HTML, JS, CSS, IMAGES

I don't have embedded files like movies or sounds, so I'm not sure what part of the order those would fall into.

The order may differ depending on your server... I'm not sure. Maybe a few others could look through their logs and post results we could have a general consensus.

troworld — Wed, 20 Nov 2002 21:18:28 +0000

It would make sense to ask the manufacturers of a particular browser that question for more precise results.

Busy — Wed, 20 Nov 2002 21:17:37 +0000

I believe the images are loaded before the backgrounds are.

But you also have to take in consideration the browser make, the layout of the page (does it have nested tables), included files (css, js, html, txt ...), if all the files are in the same folder as the .html page thats calling them, paths (full or part url) etc etc

SW Reynolds — Wed, 20 Nov 2002 21:12:28 +0000

It does seem logical that the browser would have to load HTML first, and as jammin said, it would bring in the external js next. If images are in fact retrieved sequentially, then it does make sense (to me at least) to keep the very top of the page as light as possible when planning a page layout, so the viewer quickly gets the sense that something is happening.

What I find confusing are situations where tiled backgrounds (small files) do not display until most of the rest of the page is shown. You would think that a little 5 k file would always be first, especially since it is in the tag. But on occasion, it seems to come in after other larger graphics are in place, which is in part what prompted me to ask the question.

Thanks to both of you for your input...

Mark Hensler — Wed, 20 Nov 2002 17:35:01 +0000

HTML is always loaded first. (As the URL for the images resides within the HTML) Whether or not the HTML finishes downloading before the first image is requested or not, I don't know.

The browser cannot descriminate images based on size, creation date, or anything. This is because it won't know any of that information until it has already downloaded the file.

I believe the browser will request files in the order in which they appear in the HTML. (this may happen before the HTML is completely downloaded) Then the images may finish downloading in a different order than requested, like you said, because of the way the TCP packets arrive.

jammin — Wed, 20 Nov 2002 16:08:07 +0000

i beleive it loads the html document first, then any external javascript, then images... but not quite sure... might be different for different types of browsers.