Filesystem API

The filesystem API gives low level access to the filesystem of the device. You can read, write and append to arbitrary files on the device. It's function are exposed under navigator.mozOs.

Reading a file


Promise<(DOMString or Uint8Array)> readFile(DOMString path, optional DOMString encoding = "binary");

path The raw path to the file
encoding Either 'binary' or 'utf-8'. If binary, the response is a Uint8Array. If utf-8, the response is a decoded string.
returns A promise which will resolve to a Uint8Array or string, depending on the encoding

Example:


navigator.mozOs.readFile('/data/local/user.js', 'utf-8')
  .then(content => console.log('readFile', content))
  .catch(err => console.error('readFile', err));

Writing to a file

If the file exists, the file is overwritten. If the file does not exist, it will be created.


Promise writeFile(DOMString path, (Uint8Array or DOMString) data, optional DOMString encoding = "binary");

path The raw path to the file
data The data to write to the file. A Uint8Array if binary encoding, or a string if utf-8 encoding.
encoding Either 'binary' or 'utf-8'. Has to match the data passed in.
returns A promise which will resolve when the write succeeded

Example:


navigator.mozOs.writeFile('/data/local/janos', 'Hello world', 'utf-8')
  .then(() => console.log('Write succeeded')
  .catch(err => console.error('Write failed', err));

Appending to a file

If the file exists, it appends the data passed into the file. If the file does not exist, it will be created.


Promise appendFile(DOMString path, (Uint8Array or DOMString) data, optional DOMString encoding = "binary");

path The raw path to the file
data The data to write to the file. A Uint8Array if binary encoding, or a string if utf-8 encoding.
encoding Either 'binary' or 'utf-8'. Has to match the data passed in.
returns A promise which will resolve when the append succeeded

Example:


navigator.mozOs.appendFile('/data/local/janos', '\nAnother line', 'utf-8')
  .then(() => console.log('Append succeeded')
  .catch(err => console.error('Append failed', err));

Removing a file

If the file does not exist, the promise will be rejected.


Promise removeFile(DOMString path);

path The raw path to the file
returns A promise which will resolve when the remove succeeded

Example:


navigator.mozOs.removeFile('/data/local/janos')
  .then(() => console.log('Remove succeeded')
  .catch(err => console.error('Remove failed', err));

Creating a directory


Promise createDirectory(DOMString path, optional boolean ignoreExisting = true);

path The raw path to the dictionary
ignoreExisting When true, the promise will resolve also when the directory already exists
returns A promise which will resolve when the operation succeeded

Example:


navigator.mozOs.createDirectory('/data/local/logs', true)
  .then(() => console.log('CreateDirectory succeeded')
  .catch(err => console.error('CreateDirectory failed', err));