IO

File and Stream Guide: [ nsIScriptableIO | Accessing Files | Getting File Information | Reading from Files | Writing to Files | Moving, Copying and Deleting Files | Uploading and Downloading Files | Working With Directories ]

Other documentation on files and I/O not using the unavailable nsIScriptableIO APIs: Code snippets: File I/O, Open and Save Dialogs, Reading textual data, Writing textual data, List of file-related error codes.

Files and Streams

This section describes how to access and get information about files, read from files and create and write files.

Using Files

A XUL application or extension may access files on disk, and either read or write to files. A file is accessed via a File object. To get a reference to a File object use nsIScriptableIO.getFile(). The following example will retrieve a reference to a file located in the profile directory named sample.txt.

var file = IO.getFile("Profile", "sample.txt");

The nsIScriptableIO object is a global object always available within an application or extension. It provides a number of useful functions for dealing with files.

Retrieve a File Object

For information about getting a File Object, see Accessing Files

Get Information about a File

Available information about a file include the permissions, size, and last modified date of a file. See Getting File Information for more details.

Reading from a File

For information about reading from text and binary files, see Reading from Files.

Writing to a File

For information about writing to text and binary files, see Writing to Files.

Copying and Moving Files

Files may be moved and copied on disk. For details, see Copying a File and Moving a File.

Deleting Files

To learn how to delete a file, see Deleting a File.

Open and Save Dialogs

You can show a dialog to the user to allow them to select a file to open or enter a filename for saving. For details about this, see Open and Save Dialogs.

File Errors

See File Errors for a list of errors that might occur while using files.

Working With Directories

Directories may be accessed in a similar manner using nsIScriptableIO.getFile(). For instance, in the following example, a subdirectory is retrieved. If the name 'subdirname' refers to a directory, then the returned object will refer to this directory. The returned value is still a nsIFile object, however a number of methods may be used which are only of value for subdirectories.

var file = IO.getFile("Profile", "subdirname");

For more information about using directories, see Working with Directories. Specifically, to create a directory, see Creating Directories and to retrieve a list of files or subdirectories within a directory, see Iterating over the Files in a Directory.

Upload and Download Files

Upload Files

To learn how to upload and post files to a web site, see Uploading and Downloading Files.

Download Files

To learn how to download and save a file from a web site to disk, see Downloading Files.