It is a SharePoint Framework (SPFx) demo Lists Visualizer React app based on mobx-state-tree MobX powered state container and Office UI Fabric React components. Would like to show how to separate state from view completely. No componentDidMount() hook to fetch data, no react specific Router. Independent development of stores and components as UI just renders the state. Unit test becoming very easy as you can write unit tests against the store to verify data fetching is happening without UI.
The app can work even without UI. I throw away entire rendering and app still works via console! I implemented it for SharePoint but you can definitely do it for you Single Page Apps (SPA). The app also includes mock data implementation on local Workbench.

Go to Lists Visualizer description page

Go to Lists Visualizer Video page

Go to Lightning Tools web site for more SPFx apps.