Adding persistent data to applications - Build Windows 8 Apps with HTML5 and JavaScript - page 238

It reads like you write some content to a given file and when this has been done you take different
routes, whether the operation completed successfully or with some errors. You'll be using this pattern
quite often in Windows Store applications.
Figure 10-2 shows the state of the folder now that a file has been created.
FIGURE 10-2 The newly created file viewed through Windows Explorer.
Creating your own files
The next time you go through the Add Task workflow from within TodoList and select the same file,
you'll get the following message from the file picker, as shown in Figure 10-3.
FIGURE 10-3 Trying to overwrite an existing file.