Managing Files and Directories

Learning how to read and write to files, and move and copy files and directories, is a basic data management skill:

1. To open a file, use the openStream() method of the File interface.

   The method returns a FileStream object, which is a handle to the opened file.

   var documentsDir;
   
   var testFile = documentsDir.createFile("test.txt");
      if (testFile != null) 
      {
         testFile.openStream("w", onOpenSuccess, onOpenError, "UTF-8");
      }

2. Perform all actual operations, such as reading, writing, or closing, on the file through the FileStream object based on a position attribute, which represents the current position in the file:

   function onOpenSuccess(fs)
   {
      /* Write HelloWorld to the file */
      fs.write("HelloWorld");
   
      /* Read the file content */
      fs.read(testFile.fileSize);
   
      /* Close the file */
      fs.close();
   }
   

3. To copy a file or directory, use the copyTo() method. The following example copies the files to the images/backup/ directory. Since the third parameter is set to true, any existing files with the same name in the target directory are overwritten.

   for (var i = 0; i < files.length; i++) 
   {
      documentsDir.copyTo(files[i].fullPath, "images/backup/"+files[i].name,
                          true, onsuccess, onerror);
   }
   

4. To move a file or directory, use the moveTo() method. The following example moves the files to the images/newFolder/ directory. Since the third parameter is set to false, no existing files with the same name in the target directory are overwritten.

   for (var i = 0; i < files.length; i++) 
   {
      documentsDir.moveTo(files[i].fullPath, "images/newFolder/"+files[i].name,
                          false, onsuccess, onerror);
   }