ISO 8601 Date (YYYY-MM-DD) Regex for JavaScript

What this pattern does

This page provides a well-structured, multi-part regular expression for matching iso 8601 date (yyyy-mm-dd), 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

// ISO 8601 Date (YYYY-MM-DD)
// ReDoS-safe | RegexVault — Localization > Date Formats

const iso8601DateYyyymmddRegex = /^((?:19|20)[0-9]{2})-(0[1-9]|1[0-2])-(0[1-9]|[12][0-9]|3[01])$/;

function validateIso8601DateYyyymmdd(input: string): boolean {
  return iso8601DateYyyymmddRegex.test(input);
}

// Example
console.log(validateIso8601DateYyyymmdd("2024-01-15")); // 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

Capture groups: 1=year, 2=month, 3=day. The pattern does not validate impossible dates like 2023-02-29 (non-leap year) or 2024-04-31 (April has 30 days). Validate calendar correctness with a date library.