IANA Timezone Identifier Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching iana timezone 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

// IANA Timezone Identifier
// ReDoS-safe | RegexVault — Localization > Time Formats

const ianaTimezoneIdentifierRegex = /^(?:Africa|America|Antarctica|Arctic|Asia|Atlantic|Australia|Europe|Indian|Pacific|Etc)\/[A-Za-z0-9_+\-]+(?:\/[A-Za-z0-9_+\-]+)?$/;

function validateIanaTimezoneIdentifier(input: string): boolean {
  return ianaTimezoneIdentifierRegex.test(input);
}

// Example
console.log(validateIanaTimezoneIdentifier("America/New_York")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Localization > Time Formats 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

IANA timezone database (TZDB/Olson database) is the global standard. Format: Area/Location or Area/Location/Subzone. Etc/* zones are for UTC offsets. US/*, Canada/*, US/Eastern are deprecated aliases.