Date Range (ISO 8601) Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching date range (iso 8601), 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

// Date Range (ISO 8601)
// ReDoS-safe | RegexVault — Localization > Date Formats

const dateRangeIso8601Regex = /^((?:19|20)[0-9]{2}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12][0-9]|3[01]))\/((?:19|20)[0-9]{2}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12][0-9]|3[01]))$/;

function validateDateRangeIso8601(input: string): boolean {
  return dateRangeIso8601Regex.test(input);
}

// Example
console.log(validateDateRangeIso8601("2024-01-01/2024-12-31")); // 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 group 1: start date, group 2: end date. This pattern does not validate that the start date precedes the end date — enforce that at application level. ISO 8601 also supports duration syntax (P1Y/2024-01-01) not covered here.