Working Preview testing mode
Specify whether data should be stored in Local Storage in the browser used for Working Preview or in a file on the filesystem. This setting is for debugging purposes only.
When testing a component in Working Preview, you can simulate Local Storage by saving the data in a file on the computer. This allows you to easily see what is (or isn't) being stored in Local Storage while you are developing your app.
Data can be persisted to two locations in Working Preview. The 'Browser' or the 'Filesystem'.
If data is persisted to the Browser, it will be stored in Local Storage for the embedded Google Chrome browser used for Working Preview.
If data is persisted to the file system, you can specify the location where data is stored. While you are developing your app, storing data in the file system allows you to look at what information is being stored.
The video below explains this property.
Persisting Data to Local Storage
When you build an application for disconnected operation you need to be sure that the data in the application is persisted to Local Storage so that edits that are made to any data are not lost if the application is restarted before the user has had a chance to synchronize the data with the server.