Hi Ben,
Here's the example I have been using:
I have two mjs files:
sample.mjs:
import {a} from '/testmod.mjs';
let p = 9;
var t1 = 1;
var t2 = 2;
var t3 = 3;
var t4 = 4;
var temp = 1;
temp = 2* temp;
temp = 3* temp;
temp
testmod.mjs:
export var a = 10;
export var b = 20;
export var c = 30;
Once I start debugging sample.mjs, I step over a little and reach line 5
and I get the following notification from inspector:
{
"method": "Debugger.paused",
"params": {
"callFrames": [
{
"callFrameId": "{\"ordinal\":0,\"injectedScriptId\":1}",
"functionName": "",
"functionLocation": {
"scriptId": "11",
"lineNumber": 0,
"columnNumber": 0
},
"location": {
"scriptId": "11",
"lineNumber": 5,
"columnNumber": 9
},
"url": "/sample.mjs",
"scopeChain": [
{
"type": "module",
"object": {
"type": "object",
"className": "Object",
"description": "Object",
"objectId": "{\"injectedScriptId\":1,\"id\":19}"
},
"startLocation": {
"scriptId": "11",
"lineNumber": 0,
"columnNumber": 0
},
"endLocation": {
"scriptId": "11",
"lineNumber": 10,
"columnNumber": 0
}
},
{
"type": "global",
"object": {
"type": "object",
"className": "global",
"description": "global",
"objectId": "{\"injectedScriptId\":1,\"id\":20}"
}
}
],
"this": {
"type": "undefined"
}
}
],
"reason": "other",
"hitBreakpoints": []
}
}
At this point I want to inspect variable "p". A
Debugger.evaluateOnCallFrame request to inspector with the parameter "p"
returns:
{
"id": 12,
"result":
{
"result":
{
"type": "object",
"subtype": "error",
"className": "ReferenceError",
"description": "ReferenceError: p is not defined\n at eval (eval at
<anonymous> (/sample.mjs:6:10), <anonymous>:1:1)\n at /sample.mjs:6:10",
"objectId": "{\"injectedScriptId\":1,\"id\":21}"
}
,
"exceptionDetails":
{
"exceptionId": 1,
"text": "Uncaught",
"lineNumber": 0,
"columnNumber": 0,
"scriptId": "14",
"stackTrace":
{
"callFrames":
[
{
"functionName": "",
"scriptId": "14",
"url": "",
"lineNumber": 0,
"columnNumber": 0
}
,
{
"functionName": "",
"scriptId": "11",
"url": "/sample.mjs",
"lineNumber": 5,
"columnNumber": 9
}
]
}
,
"exception":
{
"type": "object",
"subtype": "error",
"className": "ReferenceError",
"description": "ReferenceError: p is not defined\n at eval (eval at
<anonymous> (/sample.mjs:6:10), <anonymous>:1:1)\n at /sample.mjs:6:10",
"objectId": "{\"injectedScriptId\":1,\"id\":22}"
}
}
}
}
The expected outcome here would have been to see the actual value of
variable "p". I am seeing similar response for all variables declared in
sample.mjs and that is unexpected. However, the imported object "a" can
does not yield the same response. Inspector returns the right value for
"a".
At the same point if I send Runtime.getProperties request to V8 with the
current module scope's object id: '{\"injectedScriptId\":1,\"id\":19}' as
parameter, I only see the following:
{
"id": 15,
"result":
{
"result":
[
{
"name": "a",
"value":
{
"type": "number",
"value": 10,
"description": "10"
}
,
"writable": true,
"configurable": true,
"enumerable": true,
"isOwn": true
}
]
}
}
I do not see the other variables in sample.mjs in the above response.
Do you still think this is expected behavior or do you suspect there is
another issue here?
Please let me know. Any help will be great!
Thanks,
Nupoor
On Friday, June 26, 2020 at 4:11:04 AM UTC-7, Ben Noordhuis wrote:
>
> On Thu, Jun 25, 2020 at 2:35 AM Nupoor Kotasthane <nupoo...@gmail.com
> <javascript:>> wrote:
> >
> > I also notice that the 'this' object in the Debugger.CallFrame objects
> have their 'type' set to 'undefined' when debugging ES6 modules. I also
> notice that the variables declared in the starting module are missing from
> the scope when I try to inspect the scope object with
> Runtime.getProperties. Is this expected behavior?
> >
> >
> >
> > On Tuesday, June 23, 2020 at 2:56:57 PM UTC-7, Nupoor Kotasthane wrote:
> >>
> >> Hi Ben,
> >>
> >> We have embedded V8 version 6.7 in our product. We use it to run and
> debug JavaScript. While debugging scripts is working okay, debugging ES6
> modules using the inspector has this one problem. When using
> Debugger.evaluateOnCallFrame to inspect variables we keep getting an
> inspector response with reference errors saying the variables are not
> defined. This is true for all locally declared variables within the current
> scope in the "mjs" module (I do not see this problem with the imported
> module, only the importing module).
> >>
> >> It seems like symbols are not generated for the importing 'mjs' module.
> So do we have to do anything special for modules for this to work? I can
> share my example if and inspector responses if that will help.
> >>
> >> Thanks,
> >> Nupoor
>
> It's possible I'm misunderstanding you but it sounds like it's working
> as expected.
>
> ES modules run in strict mode. Function calls (not method calls) have
> `this` set to `undefined`, and top-level variables are local to the
> module, not global.
>
> If that's not what you mean, can you share some example code and
> expected vs. actual output?
>
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