FileSystemFileEntry

The FileSystemFileEntry interface of the File System API represents a file in a file system. It offers properties describing the file's attributes, as well as the file() method, which creates a File object that can be used to read the file.

Properties

Inherits the properties of its parent interface, FileSystemEntry, but has no properties unique to this interface.

Methods

file()

Creates a new File object which can be used to read the file.

Obsolete methods

createWriter()

Creates a new FileWriter object which allows writing to the file represented by the file system entry.

Basic concepts

To write content to file, create a FileWriter object by calling createWriter(). To read a file, obtain a File object representing its contents by calling file().

Example

The following code creates an empty file called "log.txt" (if it doesn't exist) and fills it with the text "Meow". Inside the success callback, event handlers are set up to handle the error error and writeend events. The text data is written to the file by creating a blob, appending text to it, and passing the blob to FileWriter.write().

function onInitFs(fs) {
  fs.root.getFile('log.txt', {create: true}, function(fileEntry) {
    // Create a FileWriter object for our FileSystemFileEntry (log.txt).
    fileEntry.createWriter(function(fileWriter) {
      fileWriter.onwriteend = function(e) {
        console.log('Write completed.');
      };
      fileWriter.onerror = function(e) {
        console.log('Write failed: ' + e.toString());
      };
      // Create a new Blob and write it to log.txt.
      var bb = new BlobBuilder();
      bb.append('Meow');
      fileWriter.write(bb.getBlob('text/plain'));
    }, errorHandler);
  }, errorHandler);
}
window.requestFileSystem(window.TEMPORARY, 1024*1024, onInitFs, errorHandler);

Specifications

This API has no official W3C or WHATWG specification.

Browser compatibility

[1] While the createWriter() method exists starting in Firefox 50, it is not supported, and immediately reports an NS_ERROR_DOM_SECURITY_ERR error to the error callback. The method was removed entirely in Firefox 52.

[2] Microsoft Edge implements this interface as part of the WebKitEntry interface, which is its name for FileSystemEntry.

See also

• File and Directory Entries API
• Introduction to the File System API