GET single byte from big binary file using JavaScript and XMLHttpRequest

Full example and testing page

For FireFox, trick is to map bytes to user part of unicode.
(Idea by mgran)

xmlhttp.open("GET", fileName, false);
xmlhttp.setRequestHeader("Range", "bytes="+position+"-"+position);
if (navigator.userAgent.indexOf("MSIE") == -1)
{
    eval("xmlhttp.overrideMimeType('text/plain; charset=x-user-defined')");
}
xmlhttp.send(null)
return xmlhttp.responseText.charCodeAt(0) & 0xFF; 

For Explorer in VBScript, because it is possible to access responseBody in VB but is not possible to overrideMimeType in IE.
(Idea by mgran's reader)

Function readbyteIE(fileName, position)
Dim xhr
Set xhr = CreateObject("Microsoft.XMLHTTP")

xhr.Open "GET", fileName, False
xhr.setRequestHeader "Range", "bytes=" & position & "-" & position
xhr.send Null

readbyteIE=AscB(MidB(xhr.responseBody, 1, 1)) 
End Function

Credits to mgran and his readers

PS: I'm new in browser scripting. Please correct me if I missed something.