Bug 174931 - Implement RegExp lookbehind assertions
Summary: Implement RegExp lookbehind assertions
Alias: None
Product: WebKit
Classification: Unclassified
Component: JavaScriptCore (show other bugs)
Version: WebKit Nightly Build
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Michael Saboff
URL: https://github.com/tc39/proposal-rege...
Keywords: InRadar
: 226465 (view as bug list)
Depends on:
Reported: 2017-07-28 00:44 PDT by Mathias Bynens
Modified: 2021-07-24 10:34 PDT (History)
17 users (show)

See Also:


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Description Mathias Bynens 2017-07-28 00:44:39 PDT
Comment 1 Radar WebKit Bug Importer 2017-07-29 11:45:21 PDT
Comment 2 Michael Saboff 2017-07-31 15:10:29 PDT
Comment 3 Masataka Yakura 2020-04-10 09:22:20 PDT
it looks like devs started to use it in the wild without fallback :(

steamcommunity.com - Page doesn't load after signing into Steam account · Issue #51385 · webcompat/web-bugs
Comment 4 md331 2020-06-04 06:50:02 PDT
ES2018 regex has landed in the beta channel of FF (https://bugzilla.mozilla.org/show_bug.cgi?id=1225665) due out end of June 2020. That'll mean Chrome, Edge, and FF support it but Safari still does not.
Comment 5 Tobias Uhlig 2021-06-19 14:01:49 PDT
I actually used it for a neo.mjs viewmodel regex and just got a heads up that dist/prod builds no longer work in safari due to this =/

Well, at first I got a report "breaks on mobile" => did not get a JS error inside my remote debugging tools, but luckily it is reproducable on desktop.

Adding this feature would be highly appreciated!

Comment 6 James Livesey 2021-06-20 05:44:22 PDT
As somebody who uses lookbehind in regex for a lot of my code, I would like to show my strong support for the resolution of this issue. Considering that all modern browsers -- save for Safari/WebKit -- support regex lookbehind, as a web developer, I find it frustrating that WebKit is the only modern browser engine which does not support this.

Which, at the moment, means that I unfortunately must resort to excluding those who use Safari/WebKit browsers from accessing some of my projects, and by extension, those who use iOS/iPadOS devices too (since the use of WebKit in any web browser is unfortunately mandatory).

From the report date, this issue has been around since 2017, so it is coming up to the 4-year anniversary of this issue existing, as of the time of writing. I hope that by giving my remarks on this issue, the WebKit developers take notice and implement this feature which really should have been added in some time ago.

According to earlier comments, it seems that many major platforms have used regex lookbehind, which completely renders sites unusable for iOS users. Though I am not an iOS, iPadOS or macOS user myself (in part because of my views on Apple's App Store browser engine policy), I would like to see this change so that iOS/iPadOS users in particular can enjoy not just my services, but others' services too.

If this issue is being worked on as we speak, I would like to therefore thank the WebKit developers in doing so.
Comment 7 Alexey Shvayka 2021-07-23 16:58:45 PDT
*** Bug 226465 has been marked as a duplicate of this bug. ***