1502665 - window.confirm() and window.prompt() always returns <undefined>

Status: RESOLVED INCOMPLETE

(Core :: DOM: Core & HTML, defect)

Description

[vraimentres]

Attachment: 스크린샷 2018-10-28 오전 3.56.10.png

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:63.0) Gecko/20100101 Firefox/63.0

Steps to reproduce:

var foo = window.confirm('hello');
console.log(foo);

var bar = window.prompt('how are you?');
console.log(bar);


Actual results:

When I press OK button to 'foo' confirm window:
> undefined

When I press Cancel button to 'foo' confirm window:
> undefined

When I enter "I'm fine." to 'bar' prompt window:
> undefined

When I press Cancel button to 'bar' prompt window:
> undefined



Expected results:

When I press OK button to 'foo' confirm window:
> true

When I press Cancel button to 'foo' confirm window:
> false

When I enter "I'm fine." to 'bar' prompt window:
> "I'm fine."

When I press Cancel button to 'bar' prompt window:
> null

Comment 1

[Andrew Overholt [:overholt]]

Hmm, I get your expected results and the same in Chrome. At first I thought it was to do with the page you were on bug google.co.kr works for me, too.

Can you make a standalone testcase?

Comment 2

[vraimentres]

(In reply to Andrew Overholt [:overholt] from comment #1)
> Hmm, I get your expected results and the same in Chrome. At first I thought
> it was to do with the page you were on bug google.co.kr works for me, too.
> 
> Can you make a standalone testcase?

The 63branch for windows works as expected, but the same 63 branch for Mac OS returns those confusing results.
I have tested this problem not only from google.com but also from some other websites. and got same "undefined" issue.

Comment 3

[Andrew Overholt [:overholt]]

Hmm, I can't reproduce on a Mac, either. Are you perhaps referring to the "<- undefined" that's echoed after the console.log statements?

Comment 4

[vraimentres]

Attachment: 스크린샷 2018-11-02 오전 1.00.48.png

Comment 5

[vraimentres]

(In reply to Andrew Overholt [:overholt] from comment #3)
> Hmm, I can't reproduce on a Mac, either. Are you perhaps referring to the
> "<- undefined" that's echoed after the console.log statements?

Oh, nope. My codes work fine in other circumstances. But Only recent version of firefox for mac makes trouble... :(

Comment 6

[Andrew Overholt [:overholt]]

I'm stumped. Maybe one of the excellent devtools team members will know.

Comment 7

[Patrick Brosset <:pbro>]

Attachment: confirm.gif

I was unfortunately unable to reproduce this problem locally.
I tested on Mac with Firefox 63, 64 and 65.
Here's a screen recording of what happens for me when I test locally.

Do you think it somehow possible that the confirm and prompt functions are overridden on the pages you tested?
Do you see the confirm and prompt dialog shown when executing these functions?
Do you see browser errors in the browser console (cmd+shift+J to open this console on mac)?

Comment 8

[Sylvestre Ledru [:Sylvestre]]

Not enough information, closing