Works in Chrome, but breaks in Safari: Invalid regular expression: invalid group specifier name /(?<=\/)([^#]+)(?=#*)/

Question

In my Javascript code, this regex /(?<=\/)([^#]+)(?=#*)/ works fine in Chrome, but in safari, I get:

Invalid regular expression: invalid group specifier name

Any ideas?

Symbolize

Related: #7376738 – Damascus

Related too: #4200657 – Damascus

It seems that Safari is not yet compliant with the 2018 standard. There's a bug report here that is over 4 years old! – Boogie

Year 2022. Still an issue with Safari – Michel

sometimes I wonder what goes on at apple – Iceboat

Hey, I'm from future, 2167 outside, still an issue – Glennisglennon

Year 2023. Still an Issue with Safari, lol. – Patrica

As of Jan 12, The latest Safari Technology Preview release 161 (bugs.webkit.org/show_bug.cgi?id=174931#c56) supports lookbehind. – Demolish

Year 2024. Still an Issue with Safari (mass release). – Recor

@SanjayVerma go back to the future! – Pyrostat

Safari, the badarse. – Sfax

year 2023-May, still an issue with safari – Silvana

Safari is the new IE – Awad

Year 2023-Aug. Still an Issue with Safari. – Effuse

Answer 1

Looks like Safari doesn't support lookbehind yet (that is, your (?<=\/)). One alternative would be to put the / that comes before in a non-captured group, and then extract only the first group (the content after the / and before the #).

/(?:\/)([^#]+)(?=#*)/

Also, (?=#*) is odd - you probably want to lookahead for something (such as # or the end of the string), rather than a * quantifier (zero or more occurrences of #). It might be better to use something like

/(?:\/)([^#]+)(?=#|$)/

or just omit the lookahead entirely (because the ([^#]+) is greedy), depending on your circumstances.

Alti

Thanks for this. I need to get the index 1 from the exec result rather than index 0. But it works. – Symbolize

Great! Works for me! To validate only numbers and one plus signal (+) (phone number with possible indicative) i have /(?<=\+.*)\+/g and changed to /(?:\+.*)\+/g. Now it works also in Safari! – Oliva

can you please help me to make this compatible with safari. /\B(?<!\.\d*)(?=(\d{3})+(?!\d))/g – Overall

I think this is a similar issue, can you please help? #68274461 – Mahlstick

Actually, this doesn't seem to be a Safari problem, but some underlying issue of the iOs operating system. This consistently breaks my pages across Safari, Chrome, Firefox and Opera (granted 3 of these use the same engine). – Golden

@AramBecker Yes, they're all built on Webkit. If Apple allowed other engines to run on their OS, some (or all) of those other engines would very likely support it by now. – Alti

Adding this to the long, long list of things to throw at people who claim that Safari is not the new Internet Explorer. – Prase

@Symbolize I have the same issue with this regex, /(\s|^)(https?:\/\/[^\s]+)(?<!\.)/. this 's used to check a string contains url format. Could you have a look for me – Amory

can we say that the non-capturing group works exactly the same as the lookbehind? – Undistinguished

@Undistinguished They serve different purposes, but you can usually refactor a pattern that includes lookbehind to one that uses a different approach to achieve the same outcome. A non-capturing group is just a logical group that you don't want to use the result of (in a backreference or in the result of the regex). – Alti

@Prase It's not the new Internet Explorer because it's always been trash. Doesn't need to supercede IE since it was terrible back in the day as well. – Shrievalty

Answer 2

Regex ?<= not supported Safari iOS, we can use ?: Note: / or 1st reference letter that comes before in a non-captured group

See detail: https://caniuse.com/js-regexp-lookbehind

let str = "Get from Slash/to Next hashtag #GMK"


let workFineOnChromeOnly = str?.match(/(?<=\/)([^#]+)(?=#*)/g)
console.log("❌ Work Fine On Chrome Only", workFineOnChromeOnly )


let workFineSafariToo = str?.match(/(?:\/)([^#]+)(?=#*)/g)
console.log("✔️ Work Fine Safari too", workFineSafariToo )

Ballottement

Answer 3

Safari added the lookbehind support in 16.4.

https://developer.apple.com/documentation/safari-release-notes/safari-16_4-release-notes#JavaScript

Archival

For the record, I still ran into this in 16.6, weirdly. – Okie

Thank you! Updating the browser solved the problem. – Deidredeific

Answer 4

The support for RegExp look behind assertions as been issued by web kit:

Check link: https://github.com/WebKit/WebKit/pull/7109

Biforate

Answer 5

Just wanted to put this out there for anyone who stumbles across this issue and can't find anything...

I had the same issue, and it turned out to be a RegEx expression in one of my dependencies, namely Discord.js .

Luckily I no longer needed that package but if you do, consider putting an issue out there or something (maybe you shouldn't even be running discord.js in your frontend react app).

Plenipotentiary