When you search for images on the Bing search engine, the result is displayed like this:
http://www.bing.com/images/search?q=stack+overflow
Notice how you can keep scrolling and scrolling and there is not "normal" paging.
My question is: How do they do this? I can see there is some ajax/javascript events happening, but the code is not easy to read. I especially would like to know how they know when an "empty box" is inside the users view port.
This feature is often called "infinite scrolling". Searching for infinite scroll javascript turns up a number of articles/posts on how to do this. Some of the more interesting ones:
Today I found a jQuery plugin that does the same scroll as Bing/Live Search:
http://blog.yctin.com/archives/jquery-plugins-ajaxscroll/
It was designed to remove the need for Next/Previous buttons.
After some searching and reading I found this very good site:
http://www.infinite-scroll.com/
It includes downloadable WordPress and jQuery -plugins and also explains pros/cons of using "Infinite scroll/autopagerize/unpaginate/endless pages"
Sample pseudo/jQuery code to load more data when user has scrolled all the way to the bottom:
Here's an article about that technology :
Eliminate paging results by using JavaScript (ala DZone) : Using Javascript, prototype and PHP.