What is it?
Script debugger is a tool to debug your runtime JavaScript errors. For most simple JavaScripts and web pages your regular tools(like a note pad) work fine. When scripts become more complex and more external scripts you have, you cannot trace the errors easily. IE is not good at handling JavaScript errors, you can try firefox or Netscape that are equipped with JavaScript debuggers. However Microsoft has a script debugger.
Audience -Any web developer or webmaster who uses JavaScript.
Where can you find it?
Freely downloadable from Microsoft site.
msdn.microsoft.com/library/en-us/sdbug/Html/sdbug_1.asp
It is also a part of visual studio suite (also a part of vs.net)
Audience -Any web developer or webmaster who uses JavaScript.
Further information
MSDN documentation on script debugger
Javascript best practices