dataURLToBlob.js

function dataURLToBlob(dataURL) {
    var BASE64_MARKER = ';base64,';

    if (dataURL.indexOf(BASE64_MARKER) == -1) {
        var parts = dataURL.split(',');
        var contentType = parts[0].split(':')[1];
        var raw = decodeURIComponent(parts[1]);

        return new Blob([raw], {type: contentType});
    }

    var parts = dataURL.split(BASE64_MARKER);
    var contentType = parts[0].split(':')[1];
    var raw = window.atob(parts[1]);
    var rawLength = raw.length;

    var uInt8Array = new Uint8Array(rawLength);

    for (var i = 0; i < rawLength; ++i) {
        uInt8Array[i] = raw.charCodeAt(i);
    }

    return new Blob([uInt8Array], {type: contentType});
}

Its loosing image orientation(making vertical image to horizontal) for portrait images taken on ios devices, how to fix this?

@Swapnilchavan18 no, it does not. It just converts data:uri object to blob, not knowing what's inside. Probably your data:uri was generated incorrectly, or blob is processed incorrectly later.