Question

How to validate an Ethereum address using Joi?

I'm working with user input validation and need to validate an Ethereum address using Joi. Can someone guide me on how to achieve this?

Answer 1

Steps to validate an Ethereum address using Joi:

Step 1: Install Joi

First, make sure you have Joi installed:

npm install joi

Step 2: Define a Custom Joi Validator for Ethereum Address

You can use Joi’s .pattern() method to create a regular expression pattern that matches an Ethereum address. The regular expression for an Ethereum address is:

It should start with 0x

It should be followed by exactly 40 hexadecimal characters (letters a-f, A-F, or digits 0-9).

Here's the code:

const Joi = require('joi');

// Define the Ethereum address validator 

const ethereumAddressSchema = Joi.string().pattern(/^0x[a-fA-F0-9]{40}$/, 'Ethereum Address')

  .message('Invalid Ethereum address. The address should start with 0x and contain 40 hexadecimal characters.');


// Example usage:

const address = '0x5B4d1b8C26A828F52C2E8B4c4C5F3e6f9077f18a';

const result = ethereumAddressSchema.validate(address);

if (result.error) {

  console.log(result.error.details[0].message);  // Validation error message

} else {

  console.log('Valid Ethereum address');

}

Step 3: Run and Test

If the address matches the pattern, the validation will pass, and you will see "Valid Ethereum address" printed in the console. If it fails (e.g., an invalid Ethereum address is provided), it will print the custom error message.

Example Invalid Address

const invalidAddress = '0x12345'; // Too short

const invalidResult = ethereumAddressSchema.validate(invalidAddress);

if (invalidResult.error) {

  console.log(invalidResult.error.details[0].message);  // "Invalid Ethereum address..."

} else {

  console.log('Valid Ethereum address');