To debug JS in Vs 2005 make sure you haven’t checked “Disable script debugging” in Internet Expolorer Option menu.
Under the Debug menu, Windows, choose Script Explorer. This should show a window on the right side with a list of the running documents. It should show the aspx page any any .js files you have included. Open up any of the .JS files and set breakpoints in your code. Once the script is executed it should stop at your breakpoints and give you all the current watch funcationality that you have come to expect from VS.NET.