Japanese Phone Number Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching japanese phone number, 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

// Japanese Phone Number
// ReDoS-safe | RegexVault — Localization > Phone Numbers

const japanesePhoneNumberRegex = /^(?:(?:\+81[\s.-]?|0)(?!0)(?=[0-9\s.-]{10,13}$)(?:[1-9][0-9]{0,3}[\s.-]?[0-9]{2,4}[\s.-]?[0-9]{4})|(?:\+81[\s.-]?|0)(?!0)(?:[1-9][0-9]{3}[\s.-]?[0-9]{1,2}[\s.-]?[0-9]{4}))$/;

function validateJapanesePhoneNumber(input: string): boolean {
  return japanesePhoneNumberRegex.test(input);
}

// Example
console.log(validateJapanesePhoneNumber("+81 3 1234 5678")); // 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

Japanese area codes: 03 (Tokyo), 06 (Osaka), 011 (Sapporo). Mobile numbers start with 070, 080, 090 (in domestic format). IP phone (050). +81 replaces the leading 0. Total 10-11 digits.