To debug JavaScript in VS.NET

1. Open Microsoft Internet Explorer.
2. On the Tools menu, click Internet Options.
3. On the Advanced tab, locate the Browsing section, and uncheck the Disable script debugging check box, and then click OK.
4. Close Internet Explorer.
   In your JavasSript function add the keyword debugger . This causes VS.NET to switch to debug mode when it runs that line.
   Run your ASP.Net application in debug mode.
   That's all there is to it.