UK NHS Number Regex for JavaScript

What this pattern does

This page provides a well-structured, multi-part regular expression for matching uk nhs number, 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

// UK NHS Number
// ReDoS-safe | RegexVault — Identity & PII > Health Identifiers

const ukNhsNumberRegex = /^([0-9]{3})[\s-]?([0-9]{3})[\s-]?([0-9]{4})$/;

function validateUkNhsNumber(input: string): boolean {
  return ukNhsNumberRegex.test(input);
}

// Example
console.log(validateUkNhsNumber("943 476 5919")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Identity & PII > Health Identifiers 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

The NHS number is 10 digits. The 10th digit is a check digit using a modulus 11 algorithm (weights 10-2). If the weighted sum's remainder is 0, the check digit is 0; if it's 1, the number is invalid; otherwise check digit = 11 - remainder.