Canvas toBlob() support added in Chrome 50

The canvas element is getting an upgrade as of Chrome 50: it now supports the toBlob() method! This is great news for anyone generating images on the client side, who wants to – say – upload them to their server, or store them in IndexedDB for future use.

function sendImageToServer (canvas, url) {

  function onBlob (blob) {
    var request = new XMLHttpRequest();
    request.open('POST', url);
    request.onload = function (evt) {
      // Blob sent to server.
    }

    request.send(blob);
  }

  canvas.toBlob(onBlob);
}

Using toBlob() is great, because instead of manipulating a base64 encoded string that you get from toDataURL(), you can now you work with the encoded binary data directly. It’s smaller, and it tends to fit more use-cases than a data URI.

If you’re wondering whether you can draw image blobs to another canvas context, the answer is – in Firefox and Chrome – yes, absolutely! You can do this with the createImageBitmap() API, which is also landing in Chrome 50.