1705557 - Inconsistent results between raw regex obj .test versus RegExp.text using the same pattern and test string

Status: RESOLVED INVALID

(Core :: JavaScript Engine, defect)

Description

[Ted]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.0.3 Safari/605.1.15

Steps to reproduce:

const regex1 = RegExp("^[a-zA-Z,\s]+$", 'g');
const str1 = 'table football, foosball';

console.log(/^[a-zA-Z,\s]+$/.test(str1));
console.log(regex1.test(str1));

Actual results:

Same pattern, Same test string results in different results between raw regex versus the RegExp obj

Expected results:

Results should have been the same. Fails in Safari and Chrome as well.

Comment 1

[Ted]

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/exec

Comment 2

[Ted]

Also,
replace using a RegExp object fails, but a raw regex expression succeeds:
var regex = new RegExp("h");
var somestring = "hello";

console.log(somestring.replace(regex, "");
console.log(somestring.replace(/h/, "");

Comment 3

[Hani Yacoub, Desktop QA]

Attachment: Screenshot 2021-04-16 at 15.37.38.png

Pasting the string from comment 1 the first time it gives: true false results and pasting it again it gives an error.
Pasting the string from comment 2 gives the same results after 2 tries: ello ello

Are these the same results you are seeing?
Thanks.

Comment 4

[Ted]

It appears the problem is only with RegExp.test (and perhaps RegExp.exec). Yes, the results for the code in the first comment that I'm getting are the same as the one you're getting. I believe the problem is in the RegExp component here and that the raw regex is behaving properly.

On the code in the second comment, apologies. There was an error in my replace code example (missing a paren at the end of the console log statement), which is why you were getting an error. However, when it is fixed, you're right - RegExp.replace and raw regex .replace both work correctly.

So, just to reiterate the bug here is with RegExp.test (I believe).

Comment 5

[Hani Yacoub, Desktop QA]

On Chrome I also get an error "Uncaught SyntaxError: Identifier 'regex1' has already been declared".
On Safari I also get "SyntaxError: Can't create duplicate variable: 'str1'".

Managed to reproduce on Windows 10 x64, macOS 10.15 and on Ubuntu 20.04 x64.
I will set a component for this bug and change the status to new.

Comment 6

[Ted]

Awesome, thanks! I'll continue to monitor.

Comment 7

[Iain Ireland [:iain]]

The problem is in this line, where the backslash is not being escaped properly:

const regex1 = RegExp("^[a-zA-Z,\s]+$", 'g');
                                ^^
                               here

If \s is replaced with \\s, then the results are as expected.

Comment 8

[Ted]

Indeed, you're correct. Oversight on my part. These damn regex strings get a bit confusing to look at after you've been looking at them for a while.

I know the regex object is different from a regex string passed to RegExp, so an escape of the slash is necessary, but for the sake of consistency, perhaps the object should behave as though it were a string. There are probably a bunch of implications I'm not thinking about right (to say nothing of backwards compatibility), but just thought I would mention it.

For now, I agree with closing this.

(In reply to Iain Ireland [:iain] from comment #7)

The problem is in this line, where the backslash is not being escaped properly:

const regex1 = RegExp("^[a-zA-Z,\s]+$", 'g');
                                                      ^^
                                                     here

If \s is replaced with \\s, then the results are as expected.