I wrote a similar instrumenting debugger for JavaScript awhile back, but haven't maintained it: https://github.com/tlrobinson/xebug https://github.com/tlrobinso

I wrote a similar instrumenting debugger for JavaScript awhile back, but haven't maintained it: https://github.com/tlrobinson/xebug https://github.com/tlrobinson/xebug At one point even I implemented the V8 debugger protocol so you could use the Web Inspector, and an HTTP proxy that would automatically instrument JavaScript files (using synchronous XMLHttpRequests to block execution...), but I don't think I ever posted that code :(