Conversion dataUri string to Blob

dataUri2Blob.js

function dataUri2Blob (dataUri) {
    var dataUriArr = dataUri.split(';base64,'),
        imageType = dataUriArr[0].replace('data:', ''),
        base64Str = dataUriArr[1],
        BlobBuilder = window.BlobBuilder || window.WebKitBlobBuilder || window.MSBlobBuilder || window.MozBlobBuilder,
        binaryString = window.atob(base64Str),
        bytes,
        arrayBuffer,
        blob;

    bytes = Array.prototype.map.call(binaryString, function(c){ return c.charCodeAt(0) & 0xff; });

    arrayBuffer = new Uint8Array(bytes).buffer;

    if (window.Blob) {
        blob = new Blob([arrayBuffer], {type : imageType});
    } else {
        blob = new BlobBuilder();
        blob.append(arrayBuffer);
        blob = blob.getBlob(imageType);
    }

    return blob;

}