@getdelta/wallet-address-validator/src/ethereum_validator.js

Wallet address validator for Bitcoin and other Altcoins.

var cryptoUtils = require('./crypto/utils');

module.exports = {
    isValidAddress: function (address) {
        if (!/^0x[0-9a-fA-F]{40}$/.test(address)) {
            // Check if it has the basic requirements of an address
            return false;
        }

        if (/^0x[0-9a-f]{40}$/.test(address) || /^0x?[0-9A-F]{40}$/.test(address)) {
            // If it's all small caps or all all caps, return true
            return true;
        }

        // Otherwise check each case
        return this.verifyChecksum(address);
    },
    verifyChecksum: function (address) {
        // Check each case
        address = address.replace('0x','');

        var addressHash = cryptoUtils.keccak256(address.toLowerCase());

        for (var i = 0; i < 40; i++ ) {
            // The nth letter should be uppercase if the nth digit of casemap is 1
            if ((parseInt(addressHash[i], 16) > 7 && address[i].toUpperCase() !== address[i]) ||
                (parseInt(addressHash[i], 16) <= 7 && address[i].toLowerCase() !== address[i])) {
                return false;
            }
        }

        return true;
    }
};