It is possible to simulate the file operations using IndexedDB API, an HTML input element with the file type, an HTML anchor element with the download attribute

It is possible to simulate the file operations using IndexedDB API, an HTML input element with the file type, an HTML anchor element with the download attribute, etc, but that would require a good understanding of these standards and careful design for a good user experience. Also, the performance may not be satisfactory for frequent operations and large files. … Based on the implementation of different browsers, one entry in the origin private file system does not necessarily map to an entry in the user’s local filesystem — it can be an object stored in some database. That means a file or directory created via the File System Access API may not be easily retrieved from outside of the browser. So what is the point of using this instead of IndexedDB, then? In IndexedDB we can even save private non-extractable keys!