The File and Directory Entries API simulates a local file system that web apps can navigate around. You can develop apps that can read, write, and create files and directories in a sandboxed, virtual file system. 
The FileSystemEntry interface of the File and Directory Entries API represents a single in a file system. The entry can be a file or a directory (directories are represented by the DirectoryEntry interface. It includes methods for working with files—including copying, moving, removing, and reading files—as well as information about a file it points to—including the file name and its path from the root to the entry.