duk4VB is an open source javascript IDE/Debugger built as an easy to use ActiveX control (OCX).

It uses the lite weight DukTape JavaScript engine and Scintilla as its IDE editor. It supports breakpoints, single stepping, syntax highlighting, brace matching, intellisense etc. All of the major features you would expect in a modern IDE environment.

It also supports basic COM integration so you can script your vb6 form and class elements! All of this open source, and within about 1 MB of disk space. I have wanted a project like this for literally a decade, and its finally here for all of us to enjoy!

An example of a live project which already uses it is IDA JScript