The npm module base62-node seems to have been renamed to base62.js, and the usage has changed slightly, so here’s a memo.

base62-node

With base62-node, we created a new object with new and used it.

> var Base62 = require('base62-node');
> var base62 = new Base62('09azAZ');
> base62.encode(123);
'1Z'

base62.js

With base62.js, it was changed to receive a converter instance using the createConverter() method.

> var base62js = require('base62.js');
> base62js
{ table_: '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ',
  createConverter: [Function: createConverter] }

> var base62 = base62js.createConverter();
> base62.encode(123);
'1Z'

That’s all from the Gemba.