I have improved the check on that line such that it now looks in substrings, try it out and let me know how it works.
We have one central place for dealing with handling ANSI coloring - in case we get more ansi feature requests we could put all those there.
Code pointer https://github.com/Microsoft/vscode/blob/master/src/vs/workbench/parts/debug/browser/debugANSIHandling.ts#L1

Thanks! Another suggestion, Chrome devtools shows a hint in the console after it's cleared, like this:

which is probably useful for knowing that there may have been output there previously. Should we consider something like that for vscode too?

I think this is useful when the console is cleared using a control character, since it is unexcpected by the user.
When the console is cleared using a user action I would not show this text. I just tried chrome and it also behaves like this.
So I will implement something like that

fyi @weinand

That sounds good. Especially because chrome devtools doesn't look for this escape code. Thanks.

One more thing :)

https://github.com/Microsoft/vscode/blob/19dcc2d86952dd01deb4162143b3eee15c1e48aa/src/vs/workbench/parts/debug/electron-browser/debugService.ts#L673

This is a literal backslash, you want '\u001b[2J', \u is a unicode escape sequence in JS.

@isidorn it would help if you would verify your code by actually running it once ;-)

E.g. by using https://www.npmjs.com/package/clear and running this:

var clear = require('clear');
clear();

@roblourens thanks rob, I pushed a fix
@weinand thanks for the example, but I tried that and the clear does not send any console output to the vscode ux, thus I could not verify with that example (and still can not)

@isidorn So how should we verify this feature then?

Have you tried console.log('hello \u001b[2J world')?
Do you understand why npmjs.com/package/clear is failing?

@weinand yes the console log example works that is how I verified
npmjs clear is failing beacuse no console output statement is coming from the debug adapter. I did not investigate inside the debug adapter as to why that is happening. I can create an independent issue if that will help?

@isidorn there is no need to investigate inside the debug adapter.
If you step through the few lines of "clear()" you will see that the sequence is sent to "process.stdout.write" instead of "console.log".
To capture the ANSI clear sequence as Output events you have to add an "outputCapture": "std" to the launch config.

Try this and verify that "clear" works with your feature.

@weinand thanks, after changing "outputCapture": "std" I can verify that the "clears" works with our feature.

Is the verification needed here that "Console was cleared" was printed? If so verified. But the original issue is about not checking for escape sequence correctly. Which I verified too I guess.

Yeah, I guess there were two parts, is the console cleared, and does it print the message.

the console is cleared even when the escape sequence is in the middle of a log string, and it does print the message, and it does log the remainder of the string after the escape sequence