Brazilian Date Format (DD/MM/YYYY) Regex for JavaScript

What this pattern does

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

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

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

function validateBrazilianDateFormatDdmmyyyy(input: string): boolean {
  return brazilianDateFormatDdmmyyyyRegex.test(input);
}

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

Brazil uses DD/MM/YYYY universally. Same regex as UK/European — apply locale context. Portuguese date format occasionally written as 15 de janeiro de 2024 (long form) which requires a different pattern.