This is an extension of https://github.com/share/sharedb/tree/master/examples/leaderboard, where DraftJS is combined with ShareDB.
Follow instructions on that repo to make the app run.
More explanation can be found here https://medium.com/@david.roegiers/building-a-real-time-collaborative-text-editor-for-the-web-draftjs-sharedb-1dd8e8826295