Card Expiry Date (MM/YY or MM/YYYY) Regex for JavaScript

What this pattern does

This page provides a well-structured, multi-part regular expression for matching card expiry date (mm/yy or mm/yyyy), ported and verified for JavaScript. Financial data validation has zero tolerance for false negatives — a missed invalid entry can corrupt downstream calculations. 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

// Card Expiry Date (MM/YY or MM/YYYY)
// ReDoS-safe | RegexVault — Finance > Card Numbers

const cardExpiryDateMmyyOrMmyyyyRegex = /^(0[1-9]|1[0-2])\/(?:20[0-9]{2}|[2-9][0-9])$/;

function validateCardExpiryDateMmyyOrMmyyyy(input: string): boolean {
  return cardExpiryDateMmyyOrMmyyyyRegex.test(input);
}

// Example
console.log(validateCardExpiryDateMmyyOrMmyyyy("01/24")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Finance > Card Numbers 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

Capture group 1: month (01-12), group 2: year (2-digit or 4-digit). 2-digit years in the range 20-99 map to 2020-2099. Cards expired but still within the grace period may still be valid — check against today's date at application level.