Develop Reference

How to manually show tab loading indicator via javascript?

I'm talking about an icon that is displayed on a tab during page loading.
Chrome:
Firefox (with TreeTab plugin):
You get the idea. I want to make it seem like the page is loading, when it's already loaded. Some event fires is javascript and then the tab looks like it's being loaded. Is there a way to do that?
One way I can think of is to replace a favicon with a spinner, but I'm not sure if it's possible to change on the fly and even if it is, it would be a hassle to make it cross-browser.

I don't think it is a good idea to do it, you'll make your users do a lot of useless requests, and this kills trees : /
IMO, it's better to do all you have in the page itself, and let the browser's UI do his own stuff.
But since I liked the challenge, here is one hacky way :
Loading an iframe will trigger this icon in both chrome and Firefox[1], so you could ,
append an iframe in the document,
set its src to some huge document,
onload of the iframe, set it again with a ? cache hack,
regularly check if the duration has elapsed so you can remove the iframe's src.
[1] It seems that Firefox does trigger the icon only if it was triggered when the document was still loading.
In code :
// how to use :
showTabLoader(25000);
// takes duration in ms as only parameter
function showTabLoader(duration) {
if (!duration) return;
var now = performance.now();
// To avoid flickering, you need some big document
// Please change this url in your script, wikimedia may not be happy with us.
var url = 'https://upload.wikimedia.org/wikipedia/commons/3/35/Viborg_Katedralskole_Symmetrical.jpg';
var iframe = document.createElement('iframe');
iframe.style.display = 'none';
document.body.appendChild(iframe);
iframe.onload = function() {
if (performance.now() - now < +duration) {
this.src = url + '?' + Math.random();
}
};
var check = function(time) {
if (time - now > +duration) {
iframe.src = '';
iframe.parentNode.removeChild(iframe);
return;
}
requestAnimationFrame(check);
}
requestAnimationFrame(check);
iframe.src = url;
}

I recently thought of the same idea. A neat option is to use a dynamic favicon instead of hacking in hidden requests, which is a really bad idea in my opinion. I found this example. It's to much code to include here and doesn't work in iframes so no way of showing it directly on Stackoverflow. Instead i describe the idea behind.
https://www.cssscript.com/favicon-loading-indicator-favloader/
The idea is simple. Replace the favicon in an interval with the loading animation icons. A favicon cannot be GIF so you have to load each image step by step with JS. When you are done, simply replace it back with the original favicon.
For me this works at least in all chrome based browsers. Firefox throw some errors in this example, but i guess it can be fixed.

Alternitive:
There is no function that shows the actual loading process of the webpage. But you can do it manually, like you said!
The event below starts to run when the page is fully loaded, even after all the images are loaded:
$(window).on('load', function() {
// do stuff
});
So what you could do is set up your html like this:
<div class="preloader">
// your loader here, animations, video, gif, anything you want
</div>
<div class="main" style="display: none;">
// the page
</div>
and your jquery like this:
$(window).on('load', function() {
setTimeout(function() {
$('.preloader').css('display', 'none');
$('.main').css('opacity', '1');
}, 5000); // <-- 5seconds
});
And there you have your manual loading function! Works perfect.
Example website: ifly50
EDIT:
added code snippet
Code snippet:
$(window).on('load', function() {
setTimeout(function() {
$('.preloader').css('display', 'none');
$('.main').css('display', 'block');
}, 3000); // <-- 3 seconds
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="preloader">loading</div>
<div class="main" style="display: none;">main</div>

How do I pick which CSS class is displayed on page load using JQuery?

I have an image version and a text version of my site logo in the following HTML tags. I want to pick which one to show based on where in the page I am vertically and the screen width.
<a class="navbar-brand" id="top-logo" href="#top"><img src="display_board.png" alt="Page Title"></a>
<a class="navbar-brand scroll" id="bottom-logo" href="#top">Page Title</a>
The following script functions correctly for screen resizing and scrolls once the page is loaded. When the site is loaded on mobile, the image logo appears first when viewing on mobile before quickly updating to the text logo, since the script file is loaded at end of the HTML file.
var method_update_nav = function() {
var buffer = 200;
var horizontal_switch_point = 1200;
var vertical_switch_point = $('.carousel-indicators').offset().top - buffer;
var window_top = Math.round($(window).scrollTop());
if ($(window).width() <= horizontal_switch_point || window_top >= vertical_switch_point) {
$('nav').removeClass('top');
$('nav').addClass('bottom');
$('#top-logo').hide();
$('#bottom-logo').show();
} else {
$('nav').removeClass('bottom');
$('nav').addClass('top');
$('#top-logo').show();
$('#bottom-logo').hide();
}
};
var main = function() {
/* UPDATE NAV */
method_update_nav();
$(window).resize(method_update_nav);
$(window).scroll(method_update_nav);
}
$(document).ready(main);
Loading the script in the HTML <header> causes the script to not function, since the classes the JQuery is referencing haven't been defined in HTML tags yet.
Is there a way to pick the correct class to show as the page loads, but after the classes have been defined in the HTML tags?

Loading the script in the HTML <header> causes the script to not function, since the classes the JQuery is referencing haven't been defined in HTML tags yet.
You say it yourself!
So you are using jQuery and I hope you know that you must place the script which references to HTML elements at the bottom of the page in:
$(document).ready(function(){
//script will now get the values because the HTML in now Loaded
})
I advise you to read some tutorials on the web.

Stop page from scolling up on link click

Fixed! Solution found on the end of this question
I've been working on a website where I have a Index page and a Info page. When you scroll down in the Index page and click the link to the Info page I want the Info page to open on the same position as the Index page was scrolled to.
I read about ScrollSneak and several similar questions and explanations here on Stackoverflow but could net get it to work for myself. I am quite a noob on javascript and am only beginning to learn how to use it. Can someone perhaps give me a example how to actually apply it to a link? I seem to fail to see what element actually links it to the actual link.
Code I found and applied below (gist link removed cause I have too low reputation to add more than 2 links xD check ScrollSneak for the file)
<!DOCTYPE html>
<html>
<head>
<!--i'm using jquery too -->
<script type="text/javascript" src="path/to/jquery.js"></script>
<!-- include scroll_sneak.js -->
<script type="text/javascript" src="path/to/scroll_sneak.js"></script>
<!-- now activate scroll sneak -->
<script type="text/javascript">
$(document).ready(function(){
var sneaky = new ScrollSneak(location.hostname);
// you want to prevent scrolling when form #my-form is submitted
document.getElementById('my-form').onsubmit = sneaky.sneak;
// or maybe you want to prevent scrolling whenever any link within
// a list-option is clicked:
$('li a').each(function(){
// note the use of 'this' instead of '$(this)', because we
// want the raw element, not the jQuery object
this.onclick = sneaky.sneak;
});
});
</script>
</head>
<body>
<img src="IMG/info_inactive.png" onmouseover="this.src='IMG/info_active.png'" onmouseout="this.src='IMG/info_inactive.png'" />
...
</body>
</html>
Overlay code Im using right now
<script>
window.addEventListener("load", function(){
var load_screen = document.getElementById("load_screen");
document.body.removeChild(load_screen);
});
</script>
SOLUTION!
I was able to find a working code on this forum topic, the submitter found it on another topic on Stackoverflow. Without futher ado, the code!
First you need a read-cookie function. Put this in the section of your page:
<script language="JavaScript">
function readCookie(name){
return(document.cookie.match('(^|; )'+name+'=([^;]*)')||0)[2]
}
</script>
Next you modify the body tag as follows:
<body onScroll="document.cookie='ypos=' + window.pageYOffset" onLoad="window.scrollTo(0,readCookie('ypos'))">
NOTE! Tested in Chrome, Firefox and Safari. "Surprisingly" this does not work in IE, but who uses IE anyway? -_-
Thanks everyone for helping me out, it is much appreciated ;)

If Taffer's solution is not working for you, you can try adding the scroll position as a get param.
(Disclosure: I do not use jquery, I prefer Mootools, but this should work)
Add an identifying class to each link you would like to scroll on the new page:
<a class="linkandscroll" href="info.html">link</a>
Then on each page, add this:
<script>
/* Method to return get params from url
thanks to: http://www.jquerybyexample.net/2012/06/get-url-parameters-using-jquery.html
*/
function getUrlParameter(sParam)
{
var sPageURL = window.location.search.substring(1);
var sURLVariables = sPageURL.split('&');
for (var i = 0; i < sURLVariables.length; i++)
{
var sParameterName = sURLVariables[i].split('=');
if (sParameterName[0] == sParam)
{
return sParameterName[1];
}
}
return false;
}
/* Method to link and set scroll get param */
function linkAndScroll(element){
/* get link element's href attribute */
var href = element.attr('href');
/* get curent scroll position */
var currentScroll = $('body').scrollTop();
/* create new url */
var url = href + '?scrollto=' + currentScroll;
/* change page location */
window.location.href = url;
}
/* on doc ready */
$(document).ready(function(){
/* loop through each scrolling link */
$('a.linkandscroll').each(function(){
/* add click event to call linkAndScroll method */
$(this).on('click', function(){
linkAndScroll($(this));
return false;
});
});
/* If scroll param is set on this page, do scroll now */
var scroll = getUrlParameter('scrollto');
if(scroll){
window.scrollTo(0, scroll);
}
});
</script>

I don't think you'll need scrollsneak, it's way more simple than that.
There are several solutions depending upon what you want, either JSRef:
<script>
function scrollWin() {
window.scrollTo(500, 0);
}
</script>
(expanded upon here: http://www.w3schools.com/jsref/met_win_scrollto.asp )
The space where it says 500 is to scroll on the X-axis(left and right), the 0 is for the Y-axis(up and down). You just change the numbers until you find the position you like.
And to make it go to another page and then execute this, you could make a script that takes some parameters like the URL of the link and specific position(or value of the element the link is contained within), and puts them into use, like so:
<script>
function linkAndScrollTo(theURL, xPos, yPos){
window.location.href = theURL;
window.scrollTo(xPos, yPos);
}
<script>
Or if you want it to scroll to a certain element in general, you can add an ID to the elements that ought to be "scrollable to", and then have the link lead to that ID on the next page. For example:
<div>
SomethingSomethingDarkside
</div>
There are probably more, I hope this answered the question.

Check browser width and execute a Javascript file and override another Javascript

There is an HTML file with many embedded YouTube videos.Page load times were slow so I decided to use this JS file to force the page load an image instead of iframe, until the user clicks on it. http://www.skipser.com/p/2/p/youtube-video-embed-like-google-plus.html
CSS checks if the visitor uses mobile and optimizes the layout for mobile.I modified the above mentioned JS script to show smaller thumbnails so it will work better on mobile(no need to scroll horizontally).I have 2 version of that JS script now.
The goal: Check if visitor uses desktop.If yes, execute the regular gplus-youtubeembed.js.If visitor uses mobile then execute gplus-youtubeembed-mobile.js
This was the original HTML.It would only load the desktop version of JS.As a result, mobile visitors would see a very large video thumbnail.
<!DOCTYPE html>
<html>
<head>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<meta name="viewport" content="width=device-width; initial-scale=1.0; user-scalable=yes">
<script src=gplus-youtubeembed.js></script>
<link rel=stylesheet type="text/css" href="css/style.css" media=screen />
<title>Page Title</title>
</head>
<body>
<h1>My First Heading</h1>
<p>My first paragraph.</p>
<script>optimizeYouTubeEmbeds()</script> <!--needed to load image instead of iframe-->
</body>
</html>
Then I used this method http://www.coalmarch.com/blog/how-to-execute-javascript-based-on-screen-size-using-jquery
if ( $(window).width() > 700) {
//added the content of gplus-youtubeembed.js here
}
else {
//added the content of gplus-youtubeembed-mobile.js here
}
I named that gplus-youtubeembed-combine.js and replaced gplus-youtubeembed.js with gplus-youtubeembed-combined.js , in the HTML doc.
The outcome: The only JS that gets executed is the mobile version.Desktop visitors see small thumbnails.Everyting works fine in mobile.Why doesn't the gplus-youtubeembed-combined.js work properly ? It's supposed to detect if the screen width is over 700 and execute the gplus-youtubeembed.js file but it doesn't.Any help is appreciated.Thanks !

From what I understand
if ( $(window).width() > 700) {
//added the content of gplus-youtubeembed.js here
}
else {
//added the content of gplus-youtubeembed-mobile.js here
}
works only when a window is first loaded or refreshed. Try changing the size of your window and refresh your page. If the code works, you'll need something to reload the script or the page on resize.
Something like this:
$(window).resize(function() {
// add the stuff here to execute the your slider again;
});
or this might do the trick:
<script>
function refresh() { location.reload(); }
</script>
<body onresize="refresh()">
I'm no expert but I had similar issue just a few minutes ago. Hope I helped.

Here is a little more detail on the second code that you asked for.
I'm only sharing with you what I'm learning as I go. I'm a real noob. Having the same problem as you but with a different snippet.
$(document).ready(function(){
$(window).on('resize', function(){
if ($(window).width() > 700) {
// code here
} esle {
// code here
}
});
});
But you said refreshing your page didn't make the JS run. Which means this method might not help you. Have you checked to make sure both JS run and work regardless of page width? Maybe test each JS individually to make sure the mobile version is good.
Sorry if I can't be much help to you. I'm learning as I try to solve my own issues. Thought yours was close to the issue I was having.

Problem was fixed.When I copy/pasted two JS files into the if/else statement, something broke the "if" statement so "else" was always being executed.I confirmed this by swapping the mobile and desktop versions and changing ">" to "<".In that case only desktop version would load.
Instead of copy/pasting the entire JS files into else/if, I left the common part out and added only the portion that was different in desktop/mobile version.Sounds simple, but it didn't come to my mind at the beginning.
The author of the original JS did not provide the mobile friendly version of the JS so people who use that code on their website might benefit from this post.One issue with the below code is that on mobile version, the image doesn't have a play button.It only has a thumbnail so make sure the visitor knows it's a video.This can be fixed by further tweaking the code but that's another topic.
Working version.
gplus-youtubeembedded-combine.js
// gplus-youtubeembed - Makes embedded YouTube video iframes Google+ style to improve page loading speed.
// Copyright (c) 2013 by Arun - http://www.skipser.com
// Licensed under the GNU LGPL license: http://www.gnu.org/copyleft/lesser.html
// For usage details, read - http://www.skipser.com/510
// Call this function at the end of the closing </body> tag.
function optimizeYouTubeEmbeds() {
// Get all iframes
var frames = document.getElementsByTagName( 'iframe' );
// Loop through each iframe in the page.
for ( var i = 0; i < frames.length; i++ ) {
// Find out youtube embed iframes.
if ( frames[ i ].src && frames[ i ].src.length > 0 && frames[ i ].src.match(/http(s)?:\/\/www\.youtube\.com/)) {
// For Youtube iframe, extract src and id.
var src=frames[i].src;
var p = /^(?:https?:\/\/)?(?:www\.)?(?:youtu\.be\/|youtube\.com\/(?:embed\/|v\/|watch\?v=|watch\?.+&v=))((\w|-){11})(?:\S+)?$/;
var id=(src.match(p) ? RegExp.$1 : false);
if(id == false) { continue;}
// Get width and height.
var w=frames[i].width;
var h=frames[i].height;
if(src == '' || w=='' || h=='') {continue;}
if ( $(window).width() > 700) {
// Thease are to position the play button centrally.
var pw=Math.ceil(w/2-38.5);
var ph=Math.ceil(h/2+38.5);
// The image+button overlay code.
var code='<div alt="For this Google+ like YouTube trick, please see http://www.skipser.com/510" style="width:'+w+'px; height:'+h+'px; margin:0 auto"><img src="http://i.ytimg.com/vi/'+id+'/hqdefault.jpg" style="width:'+w+'px; height:'+h+'px;" /><div style="background: url(\'data:image/png;base64,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\') no-repeat scroll 0 0 transparent;height: 77px;width: 77px; position:relative; margin-left:'+pw+'px; margin-top:-'+ph+'px;z-index:5;"></div></div>';
}
else {
var pw=Math.ceil(w/7.5-1.5);
var ph=Math.ceil(h/4.7+10);
var code='<div alt="For this Google+ like YouTube trick, please see http://www.skipser.com/510" style="max-width:100%;height:auto; margin:0 auto"><img src="http://i.ytimg.com/vi/'+id+'/hqdefault.jpg" style="max-width:100%;height:auto;" /> <div style="background: url(\'data:image/png;base64,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\') no-repeat scroll 0 0 transparent;height: 77px;width: 77px; position:relative; margin-left:'+pw+'px; margin-top:-'+ph+'px;z-index:5;"></div><br><br><br></div>';
}
// Replace the iframe with a the image+button code.
var div = document.createElement('div');
div.innerHTML=code;
div=div.firstChild;
frames[i].parentNode.replaceChild(div, frames[i]);
i--;
}
}
}
// Replace preview image of a video with it's iframe.
function LoadYoutubeVidOnPreviewClick(id,w ,h) {
var code='<iframe src="https://www.youtube.com/embed/'+id+'/?autoplay=1&autohide=1&border=0&wmode=opaque&enablejsapi=1" width="'+w+'" height="'+h+'" frameborder=0 allowfullscreen style="border:1px solid #ccc;" ></iframe>';
var iframe = document.createElement('div');
iframe.innerHTML=code;
iframe=iframe.firstChild;
var div=document.getElementById("skipser-youtubevid-"+id);
div.parentNode.replaceChild( iframe, div)
}
I've implemented the code here (it's my website) http://www.veryslowpc.com/security-measures.html
The outcome: in order to reduce page load times, embedded video iframes don't load until the user clicks on them, and the thumbnails are within page width when viewed on mobile.
Thank you for suggestions.
EDIT: The code should display the play button now.

How can we keep OpenX from blocking page load?

We're using OpenX to serve ads on a number of sites. If the OpenX server has problems, however, it blocks page loads on these sites. I'd rather have the sites fail gracefully, i.e. load the pages without the ads and fill them in when they become available.
We're using OpenX's single page call, and we're giving divs explicit size in CSS so they can be laid out without their contents, but still loading the script blocks page load. Are there other best practices for speeding up pages with OpenX?

We load our ads in iframes to avoid the problem you're having. We size div and the iframe the same, with the iframe pointing to a page which just contains the ad snippet (you can pass the zone and other required options as parameters to that page).
cheers
Lee

We lazy-load OpenX's code. Instead of putting the single-page call at the top of the page, we put it at the bottom. After the page has loaded, the call will get the banner data and a custom code will add the correct banners in the correct zones.
The code below requires a proper DOM. If you have jQuery, DOMAssistant, FlowJS, etc, the DOM should be fixed for you.
This code will work with normal banners with images, flash, or HTML content. It may not work in some cases like when using banners from external providers (adform, etc). For that you may need to hack the code a bit.
How to use it?
add your SinglePageCall code towards the end of your HTML code
add this code under the SPC code.
after half a second or so, your OpenX code should be ready, and the code below will put the banners within the specified DIVs.
Oh, yeah, you need to add to your HTML code some DIVs as place holders for your banners. By default I have these banners set with CSS class "hidden" which totally hides the DIVs (with visibility, display, and height). Then, after the banner in a given DIV is successfully loaded, we remove the hidden class and the DIV (and the banner within) become visible.
Use at your own risk! :) Hope it helps
(function(){
if (!document || !document.getElementById || !document.addEventListener || !document.removeClass) {
return; // No proper DOM; give up.
}
var openx_timeout = 1, // limit the time we wait for openx
oZones = new Object(), // list of [div_id] => zoneID
displayBannerAds; // function.
// oZones.<divID> = <zoneID>
// eg: oZones.banner_below_job2 = 100;
// (generated on the server side with PHP)
oZones.banner_top = 23;
oZones.banner_bottom = 34;
displayBannerAds = function(){
if( typeof(OA_output)!='undefined' && OA_output.constructor == Array ){
// OpenX SinglePageCall ready!
if (OA_output.length>0) {
for (var zone_div_id in oZones){
zoneid = oZones[zone_div_id];
if(typeof(OA_output[zoneid])!='undefined' && OA_output[zoneid]!='') {
var flashCode,
oDIV = document.getElementById( zone_div_id );
if (oDIV) {
// if it's a flash banner..
if(OA_output[zoneid].indexOf("ox_swf.write")!=-1)
{
// extract javascript code
var pre_code_wrap = "<script type='text/javascript'><!--// <![CDATA[",
post_code_wrap = "// ]]> -->";
flashCode = OA_output[zoneid].substr(OA_output[zoneid].indexOf(pre_code_wrap)+pre_code_wrap.length);
flashCode = flashCode.substr(0, flashCode.indexOf(post_code_wrap));
// replace destination for the SWFObject
flashCode = flashCode.replace(/ox\_swf\.write\(\'(.*)'\)/, "ox_swf.write('"+ oDIV.id +"')");
// insert SWFObject
if( flashCode.indexOf("ox_swf.write")!=-1 ){
eval(flashCode);
oDIV.removeClass('hidden');
}// else: the code was not as expected; don't show it
}else{
// normal image banner; just set the contents of the DIV
oDIV.innerHTML = OA_output[zoneid];
oDIV.removeClass('hidden');
}
}
}
} // end of loop
}//else: no banners on this page
}else{
// not ready, let's wait a bit
if (openx_timeout>80) {
return; // we waited too long; abort
};
setTimeout( displayBannerAds, 10*openx_timeout );
openx_timeout+=4;
}
};
displayBannerAds();
})();

OpenX has some documentation on how to make their tags load asynchronously:
http://docs.openx.com/ad_server/adtagguide_synchjs_implementing_async.html
I've tested it, and it works well in current Chrome/Firefox.
It takes some manual tweaking of their ad code. Their example of how the ad tags should end up:
<html>
<head></head>
<body>
Some content here.
Ad goes here.
<!-- Preserve space while the rest of the page loads. -->
<div id="placeholderId" style="width:728px;height:90px">
<!-- Fallback mechanism to use if unable to load the script tag. -->
<noscript>
<iframe id="4cb4e94bd5bb6" name="4cb4e94bd5bb6"
src="http://d.example.com/w/1.0/afr?auid=8&target=
_blank&cb=INSERT_RANDOM_NUMBER_HERE"
frameborder="0" scrolling="no" width="728"
height="90">
<a href="http://d.example.com/w/1.0/rc?cs=
4cb4e94bd5bb6&cb=INSERT_RANDOM_NUMBER_HERE"
target="_blank">
<img src="http://d.example.com/w/1.0/ai?auid=8&cs=
4cb4e94bd5bb6&cb=INSERT_RANDOM_NUMBER_HERE"
border="0" alt=""></a></iframe>
</noscript>
</div>
<!--Async ad request with multiple parameters.-->
<script type="text/javascript">
var OX_ads = OX_ads || [];
OX_ads.push({
"slot_id":"placeholderId",
"auid":"8",
"tid":"4",
"tg":"_blank",
"r":"http://redirect.clicks.to.here/landing.html",
"rd":"120",
"rm":"2",
"imp_beacon":"HTML for client-side impression beacon",
"fallback":"HTML for client-side fallback"
});
</script>
<!-- Fetch the Tag Library -->
<script type="text/javascript" src="http://d.example.com/w/1.0/jstag"></script>
Some other content here.
</body>
</html>

Following #Rafa excellent answer, i'm using this code to invoke OpenX banners after the page loads. I'm using jquery as well and had to add a new replace call for the "document.write" that flash banners use, and replacing it with "$('#"+ oDIV.id +"').append" instead. I'm using a custom "my_openx()" call, to replace "OA_show()". My banners area called by the zone_id and are wrapped inside a div, like this:
<div id="openx-4"><script>wm_openx(4);</script></div>
It's working :)
<script type="text/javascript">
$is_mobile = false;
$document_ready = 0;
$(document).ready(function() {
$document_ready = 1;
if( $('#MobileCheck').css('display') == 'inline' ) {
$is_mobile = true;
//alert('is_mobile: '+$is_mobile);
}
});
function wm_openx($id) {
if($is_mobile) return false;
if(!$document_ready) {
setTimeout(function(){ wm_openx($id); },1000);
return false;
}
if(typeof(OA_output[$id])!='undefined' && OA_output[$id]!='') {
var flashCode,
oDIV = document.getElementById('openx-'+$id);
if (oDIV) {
// if it's a flash banner..
if(OA_output[$id].indexOf("ox_swf.write")!=-1) {
// extract javascript code
var pre_code_wrap = "<script type='text/javascript'><!--// <![CDATA[",
post_code_wrap = "// ]]> -->";
flashCode = OA_output[$id].substr(OA_output[$id].indexOf(pre_code_wrap)+pre_code_wrap.length);
flashCode = flashCode.substr(0, flashCode.indexOf(post_code_wrap));
// replace destination for the SWFObject
flashCode = flashCode.replace(/ox\_swf\.write\(\'(.*)'\)/, "ox_swf.write('"+ oDIV.id +"')");
flashCode = flashCode.replace(/document.write/, "$('#"+ oDIV.id +"').append");
// insert SWFObject
if( flashCode.indexOf("ox_swf.write")!=-1 ) {
//alert(flashCode);
eval(flashCode);
//oDIV.removeClass('hidden');
}// else: the code was not as expected; don't show it
}else{
// normal image banner; just set the contents of the DIV
oDIV.innerHTML = OA_output[$id];
//oDIV.removeClass('hidden');
}
}
}
//OA_show($id);
}
</script>

I was looking for this to load advertising from my openX server only when the advertising should be visible. I'm using the iFrame version of openX which is loaded in a div. The answer here put me on my way to solving this problem, but the posted solution is a bit too simple. First of all, when the page is not loaded from the top (in case the user enters the page by clicking 'back') none of the divs are loaded. So you'll need something like this:
$(document).ready(function(){
$(window).scroll(lazyload);
lazyload();
});
also, you'll need to know what defines a visible div. That can be a div that's fully visible or partially visible. If the bottom of the object is greater or equal to the top of the window AND the top of the object is smaller or equal to the bottom of the window it should be visible (or in this case: loaded). Your function lazyload may look like this:
function lazyload(){
var wt = $(window).scrollTop(); //* top of the window
var wb = wt + $(window).height(); //* bottom of the window
$(".ads").each(function(){
var ot = $(this).offset().top; //* top of object (i.e. advertising div)
var ob = ot + $(this).height(); //* bottom of object
if(!$(this).attr("loaded") && wt<=ob && wb >= ot){
$(this).html("here goes the iframe definition");
$(this).attr("loaded",true);
}
});
}
Tested on all major browsers and even on my iPhone, works like a charm!!