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JS
JavaScript error

SyntaxError

The JavaScript exception "invalid property name in regular expression" or "invalid class property name in regular expression" occurs when the \p and \P Unicode character class escapes are not followed by a valid Unicode property name and/or value.

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: /\p{x}/u: Invalid property name (V8-based)
As listed by MDN Web Docs
SyntaxError: Invalid regular expression: /[\p{x}]/u: Invalid property name in character class (V8-based)
As listed by MDN Web Docs
SyntaxError: invalid property name in regular expression (Firefox)
As listed by MDN Web Docs
SyntaxError: invalid class property name in regular expression (Firefox)
As listed by MDN Web Docs
SyntaxError: Invalid regular expression: invalid property expression (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.