Ethereum Address Regex for JavaScript

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching ethereum address, 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

// Ethereum Address
// ReDoS-safe | RegexVault — Finance > Crypto

const ethereumAddressRegex = /^0x[0-9a-fA-F]{40}$/;

function validateEthereumAddress(input: string): boolean {
  return ethereumAddressRegex.test(input);
}

// Example
console.log(validateEthereumAddress("0x742d35Cc6634C0532925a3b844Bc454e4438f44e")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Finance > Crypto 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

Case-insensitive for format validation. EIP-55 checksum encoding uses mixed case — 0xAb8483... is a checksummed address. Validate checksum with web3.utils.isAddress() or ethers.js utils.getAddress().