This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

The non-standard, Firefox-specific the HTMLCanvasElement method mozGetAsFile() returns a memory-based File object representing the image contained in the canvas.


canvas.mozGetAsFile(name, type);


A DOMString indicating the file name to give the file representing the image file in memory.
type Optional
A DOMString which specifies the image file format to use when creating the new image file. The default type is image/png. For other options, see our Image file type and format guide.

Return value

A File object representing the image contained in the canvas. The file's data is entirely located in memory until such time as it is explicitly written to disk.


This example creates an image file from the <canvas> element on the page, then uses a FileReader to read the image data from the file.


<canvas id="canvas" width="100" height="100"></canvas>
<p><a href="#" id="link">Click here to try out mozGetAsFile()</a>.</p>


The following code uses mozGetAsFile() to create a File object from the canvas and appends it as an image to the page by loading it as a data URL using the readAsDataURL() method. Then a new <img> element is created using the new data URL.

function draw() {
  var canvas = document.getElementById('canvas');
  var ctx = canvas.getContext('2d');

  ctx.fillStyle = 'rgb(200, 0, 0)';
  ctx.fillRect(10, 10, 55, 50);

  ctx.fillStyle = 'rgba(0, 0, 200, 0.5)';
  ctx.fillRect(30, 30, 55, 50);

  var link = document.getElementById('link');
  link.addEventListener('click', copy);

function copy() {
  var canvas = document.getElementById('canvas');
  var f = canvas.mozGetAsFile('test.png');
  var reader = new FileReader();

  reader.onloadend = function() {
   var newImg = document.createElement('img');
   newImg.src = reader.result;

window.addEventListener('load', draw);


Not part of any specification.

Browser compatibility

ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Chrome No support NoEdge No support NoFirefox No support 4 — 74
No support 4 — 74
Notes mozGetAsFile() was deprecated in Firefox 26 (in 2013) and was removed entirely in Firefox 74.
IE No support NoOpera No support NoSafari No support NoWebView Android No support NoChrome Android No support NoFirefox Android Full support 4Opera Android No support NoSafari iOS No support NoSamsung Internet Android No support No


Full support
Full support
No support
No support
Non-standard. Expect poor cross-browser support.
Non-standard. Expect poor cross-browser support.
Deprecated. Not for use in new websites.
Deprecated. Not for use in new websites.
See implementation notes.
See implementation notes.