Canvas DataURItoBlob

dataURItoBlob.js

function dataURItoBlob(dataURI) {
  var byteString = atob(dataURI.split(',')[1]);
  var mimeString = dataURI.split(',')[0].split(':')[1].split(';')[0];
  var ab = new ArrayBuffer(byteString.length);
  var dw = new DataView(ab);
  for (var i = 0; i < byteString.length; i++) {
    dw.setUint8(i, byteString.charCodeAt(i));
  }
  return new Blob([ab], {type: mimeString});
}