RegExpMatchArray should extend [string, ...(string | undefined)[]]

[Josh-Cena]

lib Update Request

Configuration Check

My compilation target is esnext and my lib is the default.

Missing / Incorrect Definition

RegExpMatchArray extends string[], which can lead to unsound behavior.

I understand this can make string matching a little unwieldy, but it has already been unwieldy since regexps aren't generic (ref #32098, #42296), so I suggest we at least ensure correctness.

Sample Code

Playground

const match = /(a)|(b)/.exec("b");

if (match) {
  match.forEach((m) => console.log(m.toUpperCase()));
}

This fails at runtime, because when we have an alternation of capturing groups, all capturing groups will have their corresponding slot in the match array, but some values could be undefined.

Documentation Link

[Josh-Cena]

@MartinJohns May I know your point of objection? I understand you usually downvote issues that don't follow the template, but that's not the point here. So I guess it's about making string matching harder to work with?

[MartinJohns]

Because it would be a forced breaking change for a IMO rather uncommon case.

This is also intentional, see: #17053 (comment) (although the comment is quite old.)

[Josh-Cena]

Ah, I see. That issue didn't come up in my search. I guess it's still relevant today—going to close it as duplicate, then.