String convert to base64 and base58

// string -> base64
const a = Buffer.from('a', 'utf-8').toString('base64');

// base64 -> string
const b = Buffer.from(a, 'base64').toString('utf-8');

// string -> base58
-> npm i bs58 --save
const c = String('c').padStart(10,'0');
const d = base58.encode(Buffer.from(c)); // 12자리 - 10억개