Regx look behind not support firefox

Question

I am trying to search if dash exist at start or the end of the string

It working fine for Chrome but unfortunately Firefox not yet support.

Here my regex code

/^(?!-)(?!.*--)[A-Za-z0-9-]+(?<!-)$/;

I expect on Firefox also catch when the word:

-test

test-

-test-

Possible duplicate of [Javascript regex negative lookbehind not working in firefox](https://stackoverflow.com/questions/50011366/javascript-regex-negative-lookbehind-not-working-in-firefox) — Thum Choon Tat, Aug 23 '19 at 02:46
Yes similar problem but I am not so sure. how to understand that syntax and apply to my case — Mark Chhunlong, Aug 23 '19 at 02:52

score 0 · Accepted Answer · answered Aug 23 '19 at 02:46

0

Separate out the character set into two parts: one for (all but the last character) and one for (the last character), and then simply remove the - from the last character set:

/^(?!-)(?!.*--)[a-z\d-]*[a-z\d]$/i

([a-z\d] with the case-insensitive flag is equivalent to [A-Za-z0-9] without the flag)

answered Aug 23 '19 at 02:46

CertainPerformance

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Thank you so much for your answer. And also optimize my synctax. – Mark Chhunlong Aug 23 '19 at 02:54
@MarkChhunlong: Note that this pattern can be written without lookarounds at all: `/^[a-z\d]+(?:-[a-z\d]+)*$/i` – Casimir et Hippolyte Aug 23 '19 at 03:46
or why not: `/^\b(?:[a-z\d]|-\b)+$/i` (shorter but less efficient). – Casimir et Hippolyte Aug 23 '19 at 03:53
@CasimiretHippolyte Thank you so much for your concern and provide the correct answer. I am less experience with regex and couldn't determine which one is the best solution. – Mark Chhunlong Aug 23 '19 at 08:31

Regx look behind not support firefox

1 Answers1