EUI-64 (64-bit Extended Unique Identifier) Regex for JavaScript

What this pattern does

This page provides a well-structured, multi-part regular expression for matching eui-64 (64-bit extended unique identifier), 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

// EUI-64 (64-bit Extended Unique Identifier)
// ReDoS-safe | RegexVault — Web & Network > MAC Address

const eui6464bitExtendedUniqueIdentifierRegex = /^[0-9a-fA-F]{2}(?:[:-][0-9a-fA-F]{2}){7}$/;

function validateEui6464bitExtendedUniqueIdentifier(input: string): boolean {
  return eui6464bitExtendedUniqueIdentifierRegex.test(input);
}

// Example
console.log(validateEui6464bitExtendedUniqueIdentifier("00:1a:2b:ff:fe:3c:4d:5e")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Web & Network > MAC Address 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

EUI-64 is constructed from a MAC-48 by inserting ff:fe in the middle. The Universal/Local bit (bit 6 of octet 1) is flipped to form IPv6 Modified EUI-64 interface identifiers.