XUL File I/O: Write Files

Writing files in XUL isn’t that much harder than reading a file, in fact its very similar.  What a relief.  In my example I am appending the data “Appending Data” to my file.

function writeFile()
{
var data = “Appending Data”;

var filePath = “C:\\text.txt”;

var file = Components.classes[“@mozilla.org/file/local;1”]
.createInstance(Components.interfaces.nsILocalFile);
var foStream = Components.classes[“@mozilla.org/network/file-output-stream;1”]
                         .createInstance(Components.interfaces.nsIFileOutputStream);
file.initWithPath(filePath);
if ( file.exists() == false ) {
      alert(“File does not exist”);
}

foStream.init(file, 0x02 | 0x10, 00666, 0);
foStream.write(data, data.length);
foStream.close();
}

file – gets the nsILocalFile interface component, making file of type nsILocalFile
foStream – gets the nsIFileOutputStream interface component, inherited from nsIOutputStream, making foStream of type nsIFileOutputStream

• init(file, file_io_flags,file_mode_flags, behavior_flags) –

Option	Type
file	nsIFile
File_io_flags	0x01	Read only
	0x02	Write only
	0x04	Read and Write
	0x08	Create File
	0x10	Append
	0x20	Truncate
	0x40	Sync
	0x80	Exclude
File_mode_flags	00400	Read by owner
	00200	Write by owner
	00100	Execute by owner
	00040	Read by Group
	00020	Write by Group
	00010	Execute by Group
	00004	Read by Others
	00002	Write by Others
	00001	Execute by Others
* Mode flags can by added to combine flag * File_mode_flags is only applicable to UNIX based systems
Behavour_flags	0	Default

write(data, count) – sends the data string parameter to the output stream buffer, and writes the number of bytes according to count
close() – closes the stream

Not too difficult, but it is sure difficult to find the instructions and documentation