JavaScript Canvas to Blob



Canvas to Blob is a polyfill for Browsers that don’t support the standard JavaScript HTMLCanvasElement.toBlob method.

It can be used to create Blob objects from an HTML canvas element.


Install via NPM:

npm install blueimp-canvas-to-blob

This will install the JavaScript files inside ./node_modules/blueimp-canvas-to-blob/js/ relative to your current directory, from where you can copy them into a folder that is served by your web server.

Next include the minified JavaScript Canvas to Blob script in your HTML markup:

<script src="js/canvas-to-blob.min.js"></script>

Or alternatively, include the non-minified version:

<script src="js/canvas-to-blob.js"></script>


You can use the canvas.toBlob() method in the same way as the native implementation:

var canvas = document.createElement('canvas')
// Edit the canvas ...
if (canvas.toBlob) {
  canvas.toBlob(function (blob) {
    // Do something with the blob object,
    // e.g. create multipart form data for file uploads:
    var formData = new FormData()
    formData.append('file', blob, 'image.jpg')
    // ...
  }, 'image/jpeg')


The JavaScript Canvas to Blob function has zero dependencies.

However, it is a very suitable complement to the JavaScript Load Image function.


The following browsers have native support for HTMLCanvasElement.toBlob:

Browsers which implement the following APIs support canvas.toBlob() via polyfill:

This includes the following browsers:


In addition to the canvas.toBlob() polyfill, the JavaScript Canvas to Blob script exposes its helper function dataURLtoBlob(url):

// Uncomment the following line when using a module loader like webpack:
// var dataURLtoBlob = require('blueimp-canvas-to-blob')

// black+white 3x2 GIF, base64 data:
var url = 'data:image/gif;base64,' + b64
var blob = dataURLtoBlob(url)


Unit tests


The JavaScript Canvas to Blob script is released under the MIT license.