Use className="myclass" rather than setAttribute("class", "myclass")

I had to build dynamic html using javascript and I came up with this problem - setAttribute("class", "myclass") didn't work. You should use className instead. The same with setAttribute("onclick","myfunc") - will not work. You should use onclick directly.

Keeping Session Alive With ASP.NET AJAX

I needed to keep session alive as long as a customer is viewing a page, no matter if he/she clicks somewhere on the page. With asp.net ajax, this was very easy.

First, you need a ScriptManager on your page with EnablePageMethods set to true:

<form id="form1" runat="server">
<asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true" />
</form>

Second, define in your code behind a simple method that does nothing but keeps session alive like this.

[WebMethod]
[ScriptMethod]
public static void KeepAlive()
{
// just keep session alive
}

Note that you have to use WebMethod and ScriptMethod attributes to make this method avaliable for using in scripts.

Third, you have to define javascript methods to call a page method that is going to keep your session alive.

<script type="text/javascript">
function RegisterKeepAlive( sec )
{
setInterval( "PageMethods.KeepAlive( OnComplete, OnTimeOut, OnError )", sec*1000 );
}
function OnComplete( arg ) {}
function OnTimeOut( arg ){}
function OnError( arg ) {}
</script>

Last, just call RegisterKeepAlive with for example 10 seconds on load event of the body:

<body onload="RegisterKeepAlive( 10 )">

You can also use UpdatePanel with Timer control, but this way is better, because you have more options for processing timeout and errors.

Great Javascript Resources

Here are some of the javascript resources I found on the net.

Yahoo! User Interface Library - a huge library with many controls and functions, including animation, effects, menus, calendar and so on.

script.aculo.us - has some basic effects that are really nice to use like fading in, fading out, folding, shaking, pulsating and so on.

Smooth Gallery - a great piece of javascript code that is perfect for showing pictures.

Lightbox2 - great for showing photos!

Shadowbox - ideal for photos or galleries, shows even flash and movies.

Carousels for showing large content.