How to create an AJAX request with JavaScript that contains both file and post data

How can I create a HTTP request that sends one file and some post data with JavaScript that can be received by a PHP server?

I have found the following suggestion but it does not seem to be complete

xhr.open("POST", "upload.php");
var boundary = '---------------------------';
boundary += Math.floor(Math.random()*32768);
boundary += Math.floor(Math.random()*32768);
bou开发者_开发问答ndary += Math.floor(Math.random()*32768);
xhr.setRequestHeader("Content-Type", 'multipart/form-data; boundary=' + boundary);
var body = '';
body += 'Content-Type: multipart/form-data; boundary=' + boundary;
//body += '\r\nContent-length: '+body.length;
body += '\r\n\r\n--' + boundary + '\r\n' + 'Content-Disposition: form-data; name="';
body += 'myfile"; filename="'+file.fileName+'" \r\n';
body += "Content-Type: "+file.type;
body += '\r\n\r\n';
body += file.getAsBinary();
body += '\r\n'
body += '--' + boundary + '\r\n' + 'Content-Disposition: form-data; name="submitBtn"\r\n\r\nUpload\r\n';
body += '--' + boundary + '--';
xhr.setRequestHeader('Content-length', body.length);

To get this working I need to have a 'file' variable that contains an input type file field but where to put additional post data? I want to send a description text as well. suppose I would also need to use xhr.send to send the request...

Additional POST data should be placed as another Content-Disposition. Example:

Content-Type: multipart/form-data; boundary=AaB03x

--AaB03x
Content-Disposition: form-data; name="submit-name"

Larry
--AaB03x
Content-Disposition: form-data; name="files"; filename="file1.txt"
Content-Type: text/plain

... contents of file1.txt ...
--AaB03x--

Here two variables are sent: the file to be uploaded and a input with name = "submit-name" and value Larry. You could have as many Content-Dispositions as variables you would like to POST.

Of course much of the plumbing could be simplified if you used a js framework like jQuery. Here's an excellent plugin which should do the job.

Why not use jquery? It save you setting up your own XHR request.

AFAIK It's not possible to send files with XmlHttpRequest.