[Edbrowse-dev] a technique for the find-and-fix

[Kevin Carhart <kevin@carhart.net>]

I'm excited to share a discovery about one way to go about tackling a big 
and arcane site.

When I'm sitting in jdb, the JS routines that have been digested into 
memory can be echoed:

* ok(window)

a,b,c,d,e,f,blah

* blah

* function blah (a) { b = arcaneMethod(a) }

So then simple code injection is possible, so that the arguments to blah 
can become less opaque.  Just overwrite blah from the jdb command line:

* function blah (a) { exportable_a = a; b = arcaneMethod(a) }

Now I can find out about the arguments to blah:

* exportable_a

* [Object object]

And it will also be legal to pipe this argument back in:

* blah(exportable_a)

And it will also be legal to try things from that function step by step 
like:

* b=arcaneMethod(exportable_a)

In case I know blah produces a runtime error but I don't know which of 
its six subsidiary calls raises the error, now I can try each one and get 
down to the root cause more quickly!

Kevin