Timezone Abbreviation Regex for JavaScript

What this pattern does

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

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

const timezoneAbbreviationRegex = /^(?:UTC|GMT|EST|EDT|CST|CDT|MST|MDT|PST|PDT|HST|AKST|AKDT|IST|JST|KST|CST|HKT|SGT|AEST|AEDT|ACST|ACDT|AWST|NZST|NZDT|CET|CEST|EET|EEST|WET|WEST|MSK|BST|WAT|CAT|EAT|SAST)$/;

function validateTimezoneAbbreviation(input: string): boolean {
  return timezoneAbbreviationRegex.test(input);
}

// Example
console.log(validateTimezoneAbbreviation("UTC")); // 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

Timezone abbreviations are AMBIGUOUS — IST means Indian Standard Time (+05:30), Irish Standard Time (+01:00), AND Israel Standard Time (+02:00). CST means Central Standard Time (US, -06:00) AND China Standard Time (+08:00). Always prefer IANA timezone identifiers (Asia/Singapore, America/New_York).