Regex fails on RN

[sourabhv]

The RegEx /^{+\/?|\/?}+$/ fails on RN 0.61.5 with error

Invalid regular expression: Quantifier has nothing to repeat, js engine: hermes

But the regex works fine on hermes build from master.

Changing the regex to /^\{+\/?|\/?\}+$/ also works.

[avp]

RN 0.61.5 is a release from November 2019. The Hermes regex parser bug was likely fixed in the series of commits near edeef8a, which is why updating Hermes and RN should fix your issue.

Closing because the fix is already in master.

[roots-ai]

Still facing the issue on RN 0.66.0 and Hermes 0.9.0

[avp]

@roots-ai I just tested the regex given in the issue and it works in Hermes 0.9.0, which I downloaded from the releases page.

[Abrax20]

@avp I have the same issue on the new hermes version with [email protected].

I tested the regex /^[a-zA-Z0-9+/]+(?<padding>={0,2})$/ in the hermes playground

[avp]

@Abrax20 looks like that uses a named capture group, which isn't a supported feature of the Hermes RegExp engine yet.

You can check https://github.com/facebook/hermes/blob/main/doc/RegExp.md for more information on which RegExp features Hermes supports right now.

[Abrax20]

@avp Thanks your response :)!
I fixed the issue using a RegExp transform babel plugin. @roots-ai If you need a fix for the issue, please install babel-plugin-transform-modern-regexp.