//**dataURL to blob**

function dataURLtoBlob(dataurl) {

var arr = dataurl.split(','), mime = arr[0].match(/:(.*?);/)[1],

bstr = atob(arr[1]), n = bstr.length, u8arr = new Uint8Array(n);

while (n--) {

u8arr[n] = bstr.charCodeAt(n);

}

return new Blob([u8arr], { type: mime });

}

//**blob to dataURL**

function blobToDataURL(blob, callback) {

var a = new FileReader();

a.onload = function (e) { callback(e.target.result); }

a.readAsDataURL(blob);

}

//test:

//var blob = dataURLtoBlob('data:text/plain;base64,YWFhYWFhYQ==');

//blobToDataURL(blob, function (dataurl) {

// console.log(dataurl);

//});