db.Put('myKey', {some: 'data'}, (value, err) => {})

It annoys me that it reverses the standard (err, value) callback convention that everyone else uses.

An advantage of the standard is that you might have 0, or 2 or more value arguments to the callback. So you can return (err) or (err, value) or (err, value, optionalExtraValue) and it's fairly consistent.