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


The usedSpace method is used to get the total of space used by the storage (the amount of space filled by files).

The request's result is a number representing the amount of available space expressed in Bytes.


var instanceOfDOMRequest = instanceOfDeviceStorage.usedSpace();


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


var sdcard = navigator.getDeviceStorage("sdcard");

var request = sdcard.usedSpace();

request.onsuccess = function () {
  // The result is expressed in bytes, let's turn it into Gigabytes
  var size = this.result / Math.pow(10,9);

  console.log("The files on your SDCard take " + size.toFixed(2) + "GB of space.");

request.onerror = function () {
  console.warn("Unable to get the space used by the SDCard: " + this.error);


Not part of any specification.

See also