International Phone with Formatting (Liberal) Regex for JavaScript

What this pattern does

This page provides a well-structured, multi-part regular expression for matching international phone with formatting (liberal), 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

// International Phone with Formatting (Liberal)
// ReDoS-safe | RegexVault — Localization > Phone Numbers

const internationalPhoneWithFormattingLiberalRegex = /^\+?[1-9][0-9]{0,2}[\s.()-]{0,2}[0-9][0-9\s.()-]{5,15}[0-9]$/;

function validateInternationalPhoneWithFormattingLiberal(input: string): boolean {
  return internationalPhoneWithFormattingLiberalRegex.test(input);
}

// Example
console.log(validateInternationalPhoneWithFormattingLiberal("+1 (212) 555-0100")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Localization > Phone Numbers 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

Liberal pattern for accepting phone numbers from international forms. Strip all non-digits except leading + before storing. Normalize to E.164 for storage and comparison.