Jaxer allows access to individual files on the file system through the Jaxer.File class.

Instantiating a File object

We can instantiate a file object by simply newing up Jaxer.File(pathToFile). Note that creating a file object does not automatically create the equivalent object on the file system.

The Jaxer.File object will be created with 'resolved' paths, which require a full path to the referenced file system object. The following code will throw an error 'NS_ERROR_FILE_UNRECOGNIZED_PATH': var myFile = Jaxer.File('myFile.txt'); To deal with this issue, use the provided Jaxer.Dir.resolvePath(path) method which will create the required path. var filePath = Jaxer.Dir.resolvePath('myFile.txt'); var myFile = new Jaxer.File(filePath);

This will give us a JavaScript object called myFile which provides many useful methods for accessing the file on the file system.

Getting information about the file

Now that we have a file object, we can retrieve a lot of useful information about the file by simply using the provided accessor methods. The API docs contain a full description for the file objects

The most useful (or at least most commonly used) method for file objects is exists(). This provides us with a boolean value predicated on the existance of the referenced file on the file system.

// if the file doesn't exist create an empty file. if (!myFile.exists()) { myFile.create(); }

Now that we have an instantiated file object called 'myFile', we can interrogate it to get useful information about the file and its properties.

var size = myFile.size; // 0 var leaf = myFile.leaf; // myFile.txt var ext = myFile.ext; // txt var path = myFile.path; // C:\aptana\JaxerDev\public\work\myFile.txt var parentPath = myFile.parentPath; // C:\aptana\JaxerDev\public\work var dateModified = myFile.dateModified; // Wed Mar 05 2008 14:52:03 GMT-0800 (Pacific Standard Time) var URL = myFile.URL; // file:///C:/aptana/JaxerDev/public/work/myFile.txt var isDir = myFile.isDir(); // false var isFile = myFile.isFile(); // true var isExec = myFile.isExec(); // false var isSymlink = myFile.isSymlink(); // false var isWritable = myFile.isWritable(); // true var isReadable = myFile.isReadable(); // true var isHidden = myFile.isHidden(); // false var isSpecial = myFile.isSpecial(); // false

Managing files on the filesystem

Some methods are available to directly manage the files.

Creating a file

To create a file we invoke the create() method on a file object.

var myFile = new Jaxer.File(Jaxer.Dir.resolvePath('myFile.txt')); if (!myFile.exists()) { myFile.create(); }

Deleting a file

To delete a file we use the remove() method.

// if the file exists delete it if (!myFile.exists()) { myFile.remove(); }

Once you delete the file, some methods previously available on the file object will throw exceptions if accessed.

Truncating a file

To truncate a file (i.e., to empty the file), use the truncate() method.

// if the file exists truncate it if (!myFile.exists()) { myFile.truncate(); }

After truncating, the file size will be reported as 0 bytes.

Copying a file

To copy the file, use the copy() method, which will copy the file to a provided file location.

if (myFile.exists() && myFile.isReadable()) { var to = Jaxer.Dir.resolvePath('copy.txt'); myFile.copy(to); to = Jaxer.Dir.combine(Jaxer.System.tempFolder,myFile.leaf); myFile.copy(to); }

The copy() method will throw an exception if the destination file already exists.