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JS
JavaScript error

SyntaxError

The JavaScript exception "invalid character in class in regular expression" occurs when a character appears in a v-mode character class but it's not allowed to appear literally.

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: /[|]/v: Invalid character in character class (V8-based)
As listed by MDN Web Docs
SyntaxError: invalid character in class in regular expression (Firefox)
As listed by MDN Web Docs
SyntaxError: Invalid regular expression: invalid class set character (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.