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JS
JavaScript error

SyntaxError

The JavaScript exception "invalid range in character class" occurs when a character class in a regular expression uses a range, but the start of the range is greater than the end.

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: /[2-1]/: Range out of order in character class (V8-based)
As listed by MDN Web Docs
SyntaxError: invalid range in character class (Firefox)
As listed by MDN Web Docs
SyntaxError: Invalid regular expression: range out of order in character class (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.