Microsoft Script Debugger is a debugging environment that extends the functionality of Microsoft Internet Explorer 4.0 and later and Microsoft Internet Information Server (IIS). You can use the Script Debugger to browse, edit, and debug .htm and .asp files that contain Microsoft Visual Basic Scripting Edition (VBScript) or Microsoft JScript. You can also use it to combine HTML and script development and to test programs written in other languages. You can then use the Microsoft virtual machine (Microsoft VM) to run the programs and to debug scripts for any scripting language engine that supports Microsoft ActiveX debugging interfaces.
The Script Debugger provides the same functionality as traditional debuggers, including the ability to:
You can also use the Script Debugger to open and edit HTML pages. The Script Debugger supports script colorization for maximum readability.
The Script Debugger and accompanying documentation is available for download at Microsoft Windows Scripting Technologies.
You can get the debugger from the microsoft downloads page:
http://www.microsoft.com/downloads/details.aspx?FamilyId=2F465BE0-94FD-4569-B3C4-DFFDF19CCD99&displaylang=en
You'll want to save it to your machine and execute it after the download completes. I hit errors trying to run it directly (on Vista).