Baobab fetcher

fetcher.js

const client = new APIClient(); // whatever. I use https://github.com/Yomguithereal/djax-client
const store = new LocalStore(); // whatever. A localStorage abstraction

// A tree
const tree = new Baobab({
  fetchingUsers: false,
  session: null,
  data: {
    users: []
  }
});

// Creating a fetcher
const fetcher = new BaobabFetcher(tree, [
  
  // Stalking get events on the 'session' path
  {
    path: ['session'],
    
    // Function to use to trigger fetching
    get: client.getSession
  },
  
  // Stalking get events on the 'data users' path
  {
    path: ['data', 'users'],
    
    // We might want to use different functions, in order until one returns valid data
    get: [store.getUsers, client.getUsers],
    
    // If we expect specific data and don't want to consider falsey value as invalid
    expect: function(data) {
      return data.length > 1;
    },
    
    // A optional condition to be passed to trigger the fecthing
    condition: isUserLogged
  }
]);

// Possibility to add hooks to edit the state when fetching and/or errors etc.