Indonesian Postal Code Regex for JavaScript

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching indonesian postal code, 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

// Indonesian Postal Code
// ReDoS-safe | RegexVault — Localization > Postal Codes

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

function validateIndonesianPostalCode(input: string): boolean {
  return indonesianPostalCodeRegex.test(input);
}

// Example
console.log(validateIndonesianPostalCode("10110")); // 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

Indonesian postal codes: 10xxx-19xxx (Jakarta), 20xxx-29xxx (North Sumatra/Sumatra), 40xxx-49xxx (West Java), 50xxx-59xxx (Central Java), 60xxx-69xxx (East Java), 80xxx-89xxx (Bali/Nusa Tenggara). Managed by PT Pos Indonesia.