What3Words Address Regex for JavaScript

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching what3words address, ported and verified for JavaScript. Identity and credential patterns need both correctness and safety, since they're frequent targets for adversarial input. 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

// What3Words Address
// ReDoS-safe | RegexVault — Identity & PII > Location PII

const what3wordsAddressRegex = /^[a-z]+(?:\.[a-z]+){2}$/;

function validateWhat3wordsAddress(input: string): boolean {
  return what3wordsAddressRegex.test(input);
}

// Example
console.log(validateWhat3wordsAddress("filled.count.soap")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Identity & PII > Location PII 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

What3Words divides the world into 3m × 3m squares, each with a unique 3-word address. The API is proprietary. Format validation can check the 3-word pattern but validity of the address requires the W3W API. 57 trillion unique combinations globally.