javascript donwload image not working as expected

I have an image that was readed to javascript.

I used sublime text to see the image and it is like this:

enter image description here

I readed this image and generate javscript arrayBuffer of Uint8Array

Inside this arrayBuffer, i see also ffd8 ffe0 like in photo above.

Now, i need to downlaod it to local machine, i used

 var blob1 = new Blob([byteArray], {type: 'application/octet-stream'});
                var fileName1 = "cool.bin";
                function saveAs(blob, fileName) {

    var url = window.URL.createObjectURL(blob);
    var anchorElem = document.createElement("a");
    anchorElem.href = url;
    anchorElem.download = fileName;
    anchorElem.style = 'display: none';

    document.body.appendChild(anchorElem);
    anchorElem.click();

    document.body.removeChild(anchorElem);

    // On Edge, revokeObjectURL should be called only after
    // a.click() has completed, atleast on EdgeHTML 15.15048
    setTimeout(function() {
        window.URL.revokeObjectURL(url);
    }, 1000);
}

After i downlaoded this image from javascript,
I see in sublime text diffrent bytes

enter image description here

What worng with my javascript donwload code ?