Demonstrates how to handle an input string that can be optionally encoded with Base64 with Node.js v20.2.0

to_utf8_from_potential_base64_encoded.js

'use strict';

function toUtf8FromPotentialBase64Encoded(input) {
    const buffer = Buffer.from(input, 'base64');

    return (input === buffer.toString('base64'))
        ? buffer.toString('utf-8')
        : input;
}

// Usage
console.log('Base64 encoded DN is...: "' + toUtf8FromPotentialBase64Encoded('bj1Kw7NobiBEw7ZlLG91PUhleMO2cixvdT1BZG1pbmlzdHJhdG9yLGRjPWV4YW1wbGUsZGM9ZGU='));
console.log('Plain DN is............: "' + toUtf8FromPotentialBase64Encoded('n=Jóhn Döe,ou=Hexör,ou=Administrator,dc=example,dc=de'));

Expected output:

Base64 encoded DN is...: "n=Jóhn Döe,ou=Hexör,ou=Administrator,dc=example,dc=de
Plain DN is............: "n=Jóhn Döe,ou=Hexör,ou=Administrator,dc=example,dc=de