Portuguese Código Postal (CP4-3) Regex for JavaScript

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching portuguese código postal (cp4-3), 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

// Portuguese Código Postal (CP4-3)
// ReDoS-safe | RegexVault — Localization > Postal Codes

const portugueseCdigoPostalCp43Regex = /^([1-9][0-9]{3})-([0-9]{3})$/;

function validatePortugueseCdigoPostalCp43(input: string): boolean {
  return portugueseCdigoPostalCp43Regex.test(input);
}

// Example
console.log(validatePortugueseCdigoPostalCp43("1000-001")); // 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

Portugal uses a CP4+3 (7-digit total, hyphen-separated) system. 1xxx (Lisbon), 4xxx (Porto), 8xxx (Algarve). CTT (Correios de Portugal) maintains the authoritative database. The hyphen is mandatory, unlike many other countries.