Forex Currency Pair Regex for JavaScript

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching forex currency pair, ported and verified for JavaScript. Financial data validation has zero tolerance for false negatives — a missed invalid entry can corrupt downstream calculations. 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

// Forex Currency Pair
// ReDoS-safe | RegexVault — Finance > Currency & Money

const forexCurrencyPairRegex = /^([A-Z]{3})[\/\-]?([A-Z]{3})$/;

function validateForexCurrencyPair(input: string): boolean {
  return forexCurrencyPairRegex.test(input);
}

// Example
console.log(validateForexCurrencyPair("EUR/USD")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Finance > Currency & Money 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

Capture group 1: base currency, group 2: quote currency. EURUSD means 1 EUR = X USD. The slash separator is convention, not universal. Crypto pairs often omit the slash. Validate each code against ISO 4217.