Hmm... This is weird... I posted a reply at 3PM yesterday and it doesn't
look like it made it onto the group. (You didn't see it, did you?) So here
goes again, with some additional notes this time...
The problem is really much easier than all this. There's no reason to use a
lazy load plugin, and no reason to even use jQuery.
Simply use a <noscript> tag for the non-JavaScript case, and a <script> tag
with document.write() for the JavaScript case:
<noscript>
<img id="statsImg" src="stats.cfm?somevar=someval" width="1"
height="1" />
</noscript>
<script type="text/javascript">
document.write(
'<img id="statsImg" src="stats.cfm?somevar=someval&',
/* your extra stuff here, e.g.: */ 'anothervar=anotherval',
'" width="1" height="1" />'
);
</script>
Or, you can use jQuery for the dynamic image if you like. But don't try to
modify the IMG from the <noscript> section - it won't exist. Instead, add
your own IMG element with jQuery instead of document.write.
-Mike
_____
From: jquery-en@googlegroups.com [mailto:jquery...@googlegroups.com] On
Behalf Of Andy Matthews
Sent: Thursday, May 21, 2009 7:08 AM
To: jquery-en@googlegroups.com
Subject: [jQuery] Re: SOT: execute JS before a specific image loads
John...
The original intent was to render an img tag to the page which would load in
a subset of my desired data, specifically that which can easily be gotten
via interpretation of the user agent string and other items. That subset
would get added to the src of the "image" as URL key/value pairs. Then, when
jQuery was available, I'd replace the src of the image tag with additional
information, which can only be gotten via JS (resolution, bandwidth, flash
player, etc).
In my testing I was never able to get this working. However, after doing
some googling, I found the lazy load plugin. Doesn't that do pretty much
what I'm looking for? Namely prevent the loading of an image until it's
scrolled into the visible window space?
andy
_____
From: jquery-en@googlegroups.com [mailto:jquery...@googlegroups.com] On
Behalf Of John Crout
Sent: Wednesday, May 20, 2009 6:08 PM
To: jquery-en@googlegroups.com
Subject: [jQuery] Re: SOT: execute JS before a specific image loads
You won't be able to intercept the image before it is loaded but you can
block it from being rendered. Remember that JavaScript relies on the DOM.
The DOM isn't fully-defined for the page, until all of it has loaded. But
you can hide it by setting its visibilitiy to "hidden", and keep the browser
from allocating real estate for it by setting "display" to "block". (Default
is "inline").
Looking at the code you included, I don't believe there is a statistic of
interest that you cannot collect when the page you've served, is requested.
(That is, the only info the browser will have that is new, it the location
of what it renders after receiving what the server sends.) For example, the
location of everything won't be available to JavaScript until after what it
will render, has been rendered.
By the way, I'm not pretending I know your business. What I meant by "stat
of interest" is that whatever you collect, after delivering the image, that
you cannot collect when the request for the page is made, is something that
can be assumed as consistent, from request to request, even from the same
user.
Correct me if I'm incorrect about this (please).
--John Crout
On Wed, May 20, 2009 at 9:51 AM, Andy Matthews <amatth...@dealerskins.com>
wrote:
Can I intercept the loading of an image BEFORE it loads?
We're looking at using an img tag for inserting stats on our server. Here's
what I'm considering...
1) Collect certain information server side, write an img to the document
like so (note the URL vars):
<img id="statsImg" src="stats.cfm?somevar=someval" width="1" height="1" />
2) Using JS, intercept the load of this image BEFORE it takes place, and add
things to the URL vars.
This way, if JS is not present, you get the default stuff, but if JS is
present, you get extra stuff.
Anyone?
Andy Matthews
Senior Web Developer
www.dealerskins.com
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