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JS
JavaScript error

SyntaxError

The JavaScript exception "invalid regexp group" occurs when the sequence (? does not start a valid group syntax. Recognized group syntaxes that start with (? include:

Reference entryJavaScriptFetched
This is a reference entry from MDN Web Docs. A full explanation with fixes has not been written yet.

The error messages

SyntaxError: Invalid regular expression: /(?1)/: Invalid group (V8-based)
As listed by MDN Web Docs
SyntaxError: invalid regexp group (Firefox)
As listed by MDN Web Docs
SyntaxError: Invalid regular expression: unrecognized character after (? (Safari)
As listed by MDN Web Docs

Details

Category
SyntaxError
Severity
error
Runtime
both

Related errors

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Source: MDN Web Docs. Data fetched 2026-09-25T01:48:37.274Z.