const base62 = require('base62.js');

base62.encode(39134); // "abc"
base62.decode('abc'); // 39134
 
const originalTable = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
 
base62.encode(39134, originalTable); // "ABC"
base62.decode('ABC', originalTable); // 39134