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This API is available on Firefox OS for privileged or certified applications only.


The add method is used to add a file inside a given storage area.

When a file is added with this method, its name is generated automatically and is available within the request's result which is a File object.


var instanceOfDOMRequest = instanceOfDeviceStorage.add(file);


A Blob object representing the file to add (note that a File object is also a Blob object).


It returns a DOMRequest object to handle the success or error of the operation.


var sdcard = navigator.getDeviceStorage("sdcard");
var file   = new Blob(["This is a text file."], {type: "text/plain"});

var request = sdcard.add(file);

request.onsuccess = function () {
  var name =;
  console.log('File "' + name + '" successfully wrote on the sdcard storage area');

// An error typically occur if a file with the same name already exist
request.onerror = function () {
  console.warn('Unable to write the file: ' + this.error);


Not part of any specification.

See also

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 Contributors to this page: chrisdavidmills, fscholz, kscarfone, Jeremie
 Last updated by: chrisdavidmills,