Korean Date Format (YYYY년 MM월 DD일) Regex for JavaScript

What this pattern does

This page provides a well-structured, multi-part regular expression for matching korean date format (yyyy년 mm월 dd일), ported and verified for JavaScript. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your JavaScript project — whether you're validating in an Express middleware, a Next.js API route, or a client-side form.

Javascript Implementation

// Korean Date Format (YYYY년 MM월 DD일)
// ReDoS-safe | RegexVault — Localization > Date Formats

const koreanDateFormatYyyyMmDdRegex = /^((?:19|20)[0-9]{2})년\s?(0?[1-9]|1[0-2])월\s?(0?[1-9]|[12][0-9]|3[01])일$/;

function validateKoreanDateFormatYyyyMmDd(input: string): boolean {
  return koreanDateFormatYyyyMmDdRegex.test(input);
}

// Example
console.log(validateKoreanDateFormatYyyyMmDd("2024년 1월 15일")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Localization > Date Formats category and carries a ReDoS-safe certification. That matters for JavaScript developers because especially critical in long-running Node.js event loops where a ReDoS vulnerability can block the entire process. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Korean uses 년 (year), 월 (month), 일 (day). Spaces between the components are optional. The optional \s? handles both spaced and unspaced forms. Korea uses the Gregorian calendar exclusively for civil purposes.