Can regex validate dates like February 30?

No. Regex checks format and ranges for each component independently but cannot verify that a date is a real calendar day. Use a date library like date-fns or Temporal for semantic validation.

How do I match multiple date formats with one regex?

Combine patterns with alternation using the | operator, wrapping each format in a non-capturing group (?:...) so the alternation applies to the entire format.

What is the ISO 8601 date format?

ISO 8601 uses YYYY-MM-DD ordering, which is unambiguous regardless of locale. It is the recommended format for APIs, databases, and file names.

Regex Pattern for Date Formats

Date strings come in many formats and regex can catch obvious formatting errors before passing values to a date parser. This example covers ISO 8601 (YYYY-MM-DD), US format (MM/DD/YYYY), and European format (DD-MM-YYYY). Note that regex cannot validate calendar logic like leap years or month-end days — use a date library for semantic validation after the format check.

Example

/^d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12]d|3[01])$/

# ISO 8601 test cases:
2024-01-15
2024-12-31
2024-13-01
2024-00-15
not-a-date
2024-1-5
20240115

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FAQ

Can regex validate dates like February 30?: No. Regex checks format and ranges for each component independently but cannot verify that a date is a real calendar day. Use a date library like date-fns or Temporal for semantic validation.
How do I match multiple date formats with one regex?: Combine patterns with alternation using the | operator, wrapping each format in a non-capturing group (?:...) so the alternation applies to the entire format.
What is the ISO 8601 date format?: ISO 8601 uses YYYY-MM-DD ordering, which is unambiguous regardless of locale. It is the recommended format for APIs, databases, and file names.

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