Canadian Postal Code Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching canadian 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

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

const canadianPostalCodeRegex = /^([ABCEGHJKLMNPRSTVXY][0-9][ABCEGHJKLMNPRSTVWXYZ])\s?([0-9][ABCEGHJKLMNPRSTVWXYZ][0-9])$/i;

function validateCanadianPostalCode(input: string): boolean {
  return canadianPostalCodeRegex.test(input);
}

// Example
console.log(validateCanadianPostalCode("K1A 0B1")); // 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

First letter identifies the province. Invalid first letters: D, F, I, O, Q, U, W (excluded because they resemble digits in some fonts or were reserved). The letter D and I are also excluded from all positions for readability.