South African Postal Code Regex for JavaScript

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching south african 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

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

const southAfricanPostalCodeRegex = /^([0-9]{4})$/;

function validateSouthAfricanPostalCode(input: string): boolean {
  return southAfricanPostalCodeRegex.test(input);
}

// Example
console.log(validateSouthAfricanPostalCode("0001")); // 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

South African postal codes range from 0001 (Pretoria administrative offices) to 9999. Major cities: Johannesburg 2001, Cape Town 8001, Durban 4001, Pretoria 0002. Leading zeros are significant for some areas.