For the project I'm working on I have to display thousands of user grouped by team, company, accounts, resellers and, sometimes, reseller of resellers. And I need to display the hierarchy using a treeview. Unfortunately the treeview control that is available with ASP.NET 2.0 cannot handle so many "nodes" with a decent level of performance, and even if he could, an html page with some thousands of users added inside nested <ul> tags will probably be more than 1 or 2 Mb: not something you want for your web application.
Unfortunately the is no TreeView control inside the ASP.NET AJAX Control Toolkit, so I looked around for something similar to the MSDN Library contents tree.
I found a few ajax treeviews, but none of them is built as an ASP.NET Ajax control or extender:
I need something that is easy to implement, easy to understand, with a nice look&feel out-of-the-box but also easily customizable.
After a quick look at the three components above I decided to go with the Ext one.
As you can see in the image at the left (here is a live example), it's very nice looking, nice transition effects, nice loading indicator.
And it's also quite easy to implement:
Then you have to write your own ajax loader that returns a JSON formatted list of nodes.
If you want to try it yourself, you can download it here.