component-utils/state-controller.js

  1. import StateStore from './state-store';
  3. /**
  4.  * A StateController manages state for an application or component
  5.  * Subclasses extend this and expose methods that call the controller's _update method
  6.  * Controller will default create its own state store unless one is passed.
  7.  * StateController subclasses should only accept the dependencies they need via constructor
  8.  * This means the dependencies can easily be mocked and unit tested
  9.  */
  10. class StateController {
  11.   // Create's a default store if one isn't given
  12.   constructor({store = null} = {}) {
  13.     this._store = store || new StateStore();
  14.     this._update(this.defaultState);
  15.   }
  17.   get defaultState() {
  18.     return {};
  19.   }
  21.   get state() {
  22.     return this._store.state;
  23.   }
  25.   // Discourage external users from using state directly
  26.   _update(props) {
  27.     this._store.update(props);
  28.   }
  30.   subscribeUpdates(listener) {
  31.     return this._store.subscribeUpdates(listener);
  32.   }
  34.   unsubscribeUpdates(listener) {
  35.     return this._store.unsubscribeUpdates(listener);
  36.   }
  37. }
  39. export default StateController;