Domain Name (Basic Hostname) Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching domain name (basic hostname), 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

// Domain Name (Basic Hostname)
// ReDoS-safe | RegexVault — Web & Network > Domain

const domainNameBasicHostnameRegex = /^(?:[a-zA-Z0-9](?:[a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?\.)*[a-zA-Z0-9](?:[a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?$/i;

function validateDomainNameBasicHostname(input: string): boolean {
  return domainNameBasicHostnameRegex.test(input);
}

// Example
console.log(validateDomainNameBasicHostname("example.com")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Web & Network > Domain 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

Does not validate TLD existence or length. Each label limited to 63 chars per RFC 1034. Total hostname should be ≤253 chars (not enforced here).