js-cookie/js-cookie v3.0.0-beta.1 on GitHub

Removed defaults in favor of a builder: now to supply an api instance with particular predefined (cookie) attributes there's Cookies.withAttributes(), e.g.:

const api = Cookies.withAttributes({
  path: '/',
  secure: true
})
api.set('key', 'value') // writes cookie with path: '/' and secure: true...

The attributes that an api instance is configured with are exposed as attributes property; it's an immutable object and unlike defaults cannot be changed to configure the api.
The mechanism to fall back to the standard, internal converter by returning a falsy value in a custom read converter has been removed. Instead the default converters are now exposed as Cookies.converter, which allows for implementing self-contained custom converters providing the same behavior:

const customReadConverter = (value, name) => {
  if (name === 'special') {
    return unescape(value)
  }
  return Cookies.converter.read(value)
}

withConverter() no longer accepts a function as argument to be turned into a read converter. It is now required to always pass an object with the explicit type(s) of converter(s):

const api = Cookies.withConverter({
  read: (value, name) => unescape(value)
})

The converter(s) that an api instance is configured with are exposed as converter property; it's an immutable object and cannot be changed to configure the api.
The entire api instance is now immutable.