How to access JavaScript execution trace at runtime in Firefox?

[SK]

I want to know how to access JavaScript execution trace at runtime. I saw Firebug can do something like this:

Refer to the image above, all the line numbers executed are highlighted in green. They are achieved at runtime. I guess there must be some way to access those info from the JavaScript engine used by the browser.

Say now I want to build a firebug plugin to access those info and examine all the variables in each executed line at the runtime, how should I do?

Thank you!

[Jan Honza Odvarko]

Firebug is currently using JSD (jsdIDebuggerService) to figure out,
which line
is executable. However, the plan is to switch to JSD2 (work in
progress)
https://wiki.mozilla.org/Debugger

You should also base your extension on JSD2

Look for getLineOffsets(line) and getOffsetLine(offset) in the
Debugger document.
I didn't test it, but I think that if getLineOffset returns null, the
line is not executable.

Honza

[MMTY]

Thank you. Is it possible to get the line execution trace in order? getLineOffsets() is just used to tell whether the line is executed or not.

Thanks

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[Jan Honza Odvarko]

On Mar 19, 7:34 pm, MMTY <kheathe...@gmail.com> wrote:
> Thank you. Is it possible to get the line execution trace in
> order?

What do you mean by order?

> getLineOffsets() is just used to tell whether the line is executed
> or not.

Note that it should say whether the line is "executable" (not
executed)

Honza


>
> Thanks

[MMTY]

Hi Honza

Thank you for your reply.

Look at this example:

#1 function callMe(){ 

#2 if(true){

#3   var a = 1;

#4   var b = 2;

#5 }else{

#6   var c = 10;

#7 }

#8 }

#9 callMe();

I want to develop a extension for firebug to add some debugging functionality that can give the execution trace in order, so the result will look like this:

#9 -> #1 -> #2 -> #3 -> #4

I looked through the firebug code and the JSD component. The getLineOffsets() only check if the line is valid for execution.

A way to approach this is to set breakpoints on all lines and keep resuming the JS. So when the breakpoints are reached, the JSD setbreakpointHook can tell the frame info. However, it is quite slow and unpractical.

Any thoughts? Thank you!

[MMTY]

And on the reslut(#9 -> #1 -> #2 -> #3 -> #4), I will also want to know the time the line is executed. 

Thanks!

[Jan Honza Odvarko]

> > A way to approach this is to set breakpoints on all lines and keep
> > resuming the JS. So when the breakpoints are reached, the JSD
> > setbreakpointHook can tell the frame info. However, it is quite slow
> > and unpractical.

I don't know about any better way.

> I will also want to know the time the line is executed.

There is now time-stamp coming from JSD2 so, you'll need to
use (new Date()).getTime()

You can also take a look at the built in profiler...
https://developer.mozilla.org/en-US/docs/Performance/Profiling_with_the_Built-in_Profiler

Honza

[Simon Lindholm]

(new Date()).getTime()

 

(Or performance.now().)

[Jan Honza Odvarko]

I have yet asked on IRC and got this answer:

Honza: take a look at JSOPTION_PCCOUNT, djf and I used that to
implement a command line coverage tool called covermonkey a while back

I didn't checked that out, but figured out that you could be
interested...

Honza

On Mar 22, 7:11 pm, Simon Lindholm <simon.lindhol...@gmail.com> wrote:
> > (new Date()).getTime()
>
> (Or performance.now().)
>
> Den fredagen den 22:e mars 2013 kl. 16:15:09 UTC+1 skrev Jan Honza Odvarko:
>
>
>
>
>
>
>
>
>
> > > > A way to approach this is to set breakpoints on all lines and keep
> > > > resuming the JS. So when the breakpoints are reached, the JSD
> > > > setbreakpointHook can tell the frame info. However, it is quite slow
> > > > and unpractical.
> > I don't know about any better way.
>
> > > I will also want to know the time the line is executed.
> > There is now time-stamp coming from JSD2 so, you'll need to
> > use (new Date()).getTime()
>
> > You can also take a look at the built in profiler...
>

> >https://developer.mozilla.org/en-US/docs/Performance/Profiling_with_t...

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