The "client library" being referred to is an autogenerated API client, like https://github.com/swagger-api/swagger-js.

Recent DRF releases have been building the CoreAPI schema definition format, which is a generic schema language like OpenAPI (nee Swagger) or API Blueprint.

The other headline DRF feature (API docs) also builds on the CoreAPI schema.

If you prefer existing standards, you can map your DRF API to Swagger using https://github.com/marcgibbons/django-rest-swagger/, and then use swagger-js (or swagger-codegen) to generate client implementations -- though the django-rest-swagger project is currently partially broken due to having migrated to CoreAPI before the latter obtained feature-parity with Swagger; the 0.3 version is more full-featured.