Working with File in browser and transform base64 back to File Object

File_base64.js

var blob = dataURItoBlob(res);
var fd = new FormData(document.forms[0]);
fd.append("canvasImage", blob);

var file = dataURLtoFile(res, 'a.jpeg');

function dataURItoBlob(dataURI) {
    var binary = atob(dataURI.split(',')[1]);
    var array = [];
    for(var i = 0; i < binary.length; i++) {
        array.push(binary.charCodeAt(i));
    }
    return new Blob([new Uint8Array(array)], {type: 'image/jpeg'});
}

function dataURLtoFile(dataurl, filename) {
    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 File([u8arr], filename, {type:mime});
}