ajax request to download an excel file is showing me truncated response

I am trying to download an Excel file using Ajax (XMLHttpRequest).

On completion the responseText is found to have just 5 characters.

The network sniffing tool (Fiddler) is showing me that my computer received the entire file..

so why is the responseText showing me only 5 characters? I have tried both Synch and Asynch calls.

Thanks for any help you can give here.

var xmlHttpReq = getXmlHttpRequestObject();

function  getXmlHttpRequestObject(){
    var xmlhttp;

    if (window.XMLHttpRequest){// code for all new browsers
          xmlhttp=new XMLHttpRequest();

    }else if (window.ActiveXObject){// code for IE5 and IE6
         // xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");

        progids = ['MSXML2.XM开发者_StackOverflow社区LHTTP.6.0', 'MSXML2.XMLHTTP.3.0', 'Microsoft.XMLHTTP'];

        for (i=0 ; i < progids.length; i ++){
            try {
                xmlhttp = new window.ActiveXObject(progids[i]);
                break;
            } catch (e) {
              //do nothing
            }
        }


    }


    return xmlhttp;


}

//utility method for http get
function doSynchronousGet(url){
    if(xmlHttpReq == null){
        xmlHttpReq = getXmlHttpRequestObject();
    }

    //change last param to true for making async calls.
    xmlHttpReq.open("GET" ,url,false);
    xmlHttpReq.setRequestHeader("Connection", "close");
    xmlHttpReq.send(null);
    return xmlHttpReq.responseText;
}



var resultText = doSynchronousGet(url);

alert('resultText length: '+ resultText.length);
alert('resultText: '+ resultText);

The issue is probably that XMLHttpRequest doesn't ususally take binary data like an Excel file. If you just want to let the user download the file, read Ramiz's post. If you need to read the data in JavaScript, try switching to a text format like CSV (or better for parsing, JSON). If you really need to read a binary file, there are discussions of that here and here.

Do not use Ajax call (xmlhttprequest) to download/upload files. Better do it on server side.