Korean Postal Code (5-digit, post-2015) Regex for JavaScript

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching korean postal code (5-digit, post-2015), 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 Postal Code (5-digit, post-2015)
// ReDoS-safe | RegexVault — Localization > Postal Codes

const koreanPostalCode5digitPost2015Regex = /^[0-9]{5}$/;

function validateKoreanPostalCode5digitPost2015(input: string): boolean {
  return koreanPostalCode5digitPost2015Regex.test(input);
}

// Example
console.log(validateKoreanPostalCode5digitPost2015("03000")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Localization > Postal Codes 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

South Korea switched from the old 6-digit format (XXX-XXX) to a new 5-digit system in August 2015. The old format is no longer valid for new addresses. North Korea is not covered by this system.