You often see some of the dirty codes on the top when you viewsource on the browser. These are the datas that are inserted to manage viewstate.

The ViewState property is defined in the “System.Web.UI.Control” class. Since all ASP.NET pages and controls derive from this class, they all have access to the ViewState property. The type of the ViewState property is “System.Web.UI.StateBag”.

The very special thing about the StateBag class is the ability to “track changes”. Tracking is, by nature, off; it can be turned on by calling the “TrackViewState()” method. Once tracking is on, it cannot be turned off. Only when tracking is on, any change to the StateBag value will cause that item to be marked as “Dirty”.

By default viewstate data stays at the top when you viewsource on the browser.This dirty codes makes your site not accepted by the crawlers as SEO.

You can instruct the asp.net engine to render the viewstate data on the bottom so that crawler can first read your actual content rather than these dirty codes and makes your site search engine optimized. Here is the code to do so.

Download code

protected override void Render(HtmlTextWriter writer)

{

System.IO.StringWriter stringWriter = new System.IO.StringWriter();

HtmlTextWriter htmlWriter = new HtmlTextWriter(stringWriter);

base.Render(htmlWriter);

string html = stringWriter.ToString();

int StartPoint = html.IndexOf("<input type=\"hidden\" name=\"__VIEWSTATE\" id=\"__VIEWSTATE\"");

if (StartPoint <= 0)

{

//does __viewstate exist?

int EndPoint = html.IndexOf("/>", StartPoint) + 2;

string viewstateInput = html.Substring(StartPoint, EndPoint - StartPoint);

html = html.Remove(StartPoint, EndPoint - StartPoint);

int FormEndStart = html.IndexOf("</form>") - 1;

if (FormEndStart >= 0)

{

html = html.Insert(FormEndStart, viewstateInput);

}

}

writer.Write(html);

}