IPv6 Link-Local Address Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching ipv6 link-local address, 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

// IPv6 Link-Local Address
// ReDoS-safe | RegexVault — Web & Network > IPv6

const ipv6LinklocalAddressRegex = /^[Ff][Ee][89AaBb][0-9a-fA-F](?::[0-9a-fA-F]{0,4}){0,7}(?:%[a-zA-Z0-9_.-]{1,20})?$/;

function validateIpv6LinklocalAddress(input: string): boolean {
  return ipv6LinklocalAddressRegex.test(input);
}

// Example
console.log(validateIpv6LinklocalAddress("fe80::1")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Web & Network > IPv6 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 fe80::/10 block means the first 10 bits are 1111111010, which covers fe80 through febf. The [89AaBb] in position 3 covers the valid second-nibble range for this prefix.