V8 debugging breakpoints in VSCode

[boukestam]

I'm trying to debug my javascript code with the VSCode debugger.
I have constructed my engine with the following code:

_engine = new V8ScriptEngine(V8ScriptEngineFlags.EnableDebugging, 9222);

And added the following to my launch.json:

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Attach to ClearScript V8 on port 9222",
            "type": "node",
            "request": "attach",
            "protocol": "inspector",
            "address": "localhost",
	    "port": 9222
        }
    ]
}

After starting my C# application and starting the debugger in vscode I try to set some breakpoints in javascript. But the breakpoints are not being verified (not turning red). If I then trigger the debugger with the following line:

debugger;

VSCode breaks on that line as expected. From that moment on I can successfully place and trigger breakpoints in VSCode, they are also being verified (turning red). But at any point before triggering that first debugger statement, no breakpoints are being verified.

[ClearScriptLib]

Hi @boukestam,

Without the debugger statement, what is your application doing when you attach the debugger? Is it already running the script in which you're trying to set a breakpoint?

Thanks!

[boukestam]

Yes, it is already running. I'm running an ASP.NET webserver, so whenever a new request comes in I call a callback function defined in the javascript. While debugging this problem I repeatedly refreshed the page to call the callback function again. After putting a debugger statement in that function and triggering it, breakpoints suddenly started working.

[ClearScriptLib]

Hmm, what is your ClearScript version? Did you build it yourself? Any modifications relative to the official source?

[boukestam]

I'm using version 5.5.2 from nuget. Without any modifications.
I've noticed that when the debugger statement triggers it opens a new tab of the same source file with the annotation "read-only core module".

I'm not sure why this happens, because the path passed to the V8ScriptEngine.Compile function is the same as my local file.

[ClearScriptLib]

ClearScript currently strips paths out of documentName arguments (see Issue #46), so setting breakpoints in a script opened from the file system may not work.

You should be able to set breakpoints in any script opened from the "Loaded Scripts" section of VSC's "Debug" panel. Can you confirm that?

[boukestam]

Hi, sorry for my late reply. Yes it works when I open the script from the loaded scripts section in vscode. However, this is not the expected behavior and will be difficult to explain to my developers. I see that issue #46 has the same problem, but I'd rather not change the source as it makes it harder to update. Will there be a fix for this soon?

[ClearScriptLib]

No guarantees, but hopefully, yes. The next source release should be out in a few weeks, and we’ll try to include a back-compatible fix for this.

[ClearScriptLib]

Closing as duplicate of #46.

[iddm]

I have a V8 engine running with the debugger. I can connect to it using the chromium browser and the inspector integrated into it, however, I would like to use vscode to connect to the remote inspector server. The example in the first post here is not working, and it complains on the "protocol" field. Has anything changed? How can one debug the javascript code using a remote server with the inspector protocol these days?

[ClearScriptLib]

Hi @vityafx,

The example in the first post here is not working, and it complains on the "protocol" field. Has anything changed?

It looks like the protocol property is obsolete and no longer allowed. Please remove it and try again.

Good luck!