How can FMS create a text file and write data into it in the Server application folders?

Question

Recently, I writed a programe about creating a text file and writing data into it in the server application folder. My code is as following:
           var fileObj = new File("/MyApp/test.txt");
           if( fileObj !=  null)
                  if(fileObj.open( "text", "append"))
                        fileObj.write( "                                                      ———— Chat Info Backup ————\r\n" );
                        fileObj.close( );
                        trace("Chat info backup document :" +  fileObj.name + " has been created successfully!");    
But when I run it, FMS throw the error as following: File operation open failed  ;  TypeError: fileObj has no properties.
Can you help me ? Thanks in advance.
Supplement: The text file named test.txt doesn't exist before create the fileObj, an instance of File Class.

Answer 1

Is MyApp the name of the application directory, or is it a child of the application directory? If myApp is the app name, just use test.txt as the path flag in the file constructor.